Masterbatch resin composition for food packaging material, thermoplastic resin composition for food packaging material, and food packaging material

Abstract

Provided is a masterbatch resin composition for food packaging material, said masterbatch resin composition comprising a polyolefin resin (A), a basic filler (B) which has a pH of 10.0-13.0 in water and which has a water content of not more than 20,000 ppm, and an antioxidant (C) which is at least one antioxidant selected from the group consisting of hindered amine-based antioxidants, hydroxylamine-based antioxidants, and phosphorus-based antioxidants, wherein the content of the antioxidant (C) is 0.1-450 parts by mass with respect to 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 3-50 mass% based on the total mass of the masterbatch resin composition.

Description

Masterbatch resin composition for food packaging materials, thermoplastic resin composition for food packaging materials and food packaging materials

[0001] This disclosure relates to a masterbatch resin composition for food packaging materials, a thermoplastic resin composition for food packaging materials, and food packaging materials.

[0002] In recent years, there has been a growing demand to extend the shelf life of food products from the perspective of reducing food waste. However, it is difficult to suppress the growth of microorganisms in food using conventional food packaging materials alone, and as storage periods lengthen, food deterioration and spoilage occur. Therefore, conventional food packaging methods include measures such as incorporating freshness-preserving agents inside the packaging material.

[0003] In particular, for fresh foods such as fish, vegetables, and fruits, measures are being considered to impart antibacterial properties and carbon dioxide absorption capabilities to the food packaging materials themselves as a way to maintain freshness.

[0004] As an example of such technology, Patent Document 1 describes a method for creating a food packaging material with excellent freshness preservation performance by including calcium hydroxide powder, which is a basic filler, in a thermoplastic resin. Patent Document 2 describes a technology for a film that prevents deterioration of color and contamination of processing machines by including alkaline earth metal hydroxides and phenolic antioxidants in a polypropylene resin.

[0005] Polyolefin resins have become commonly used in recent years due to their high processability, appearance, chemical resistance, and excellent suitability for food packaging applications. Polyolefin resins are typically heated, melted, and kneaded using an extruder or similar device at processing temperatures of 150 to 300°C, then pelletized and processed into the shape of food packaging materials. On the other hand, basic fillers are known to inhibit the growth of microorganisms when in contact with food, thereby preserving the freshness of the food.

[0006] Japanese Patent Publication No. 2017-30842 Japanese Patent Publication No. 2001-247728

[0007] When using a masterbatch resin composition in a food packaging material manufacturing method, dispersion steps are usually required at two stages: during manufacturing and during molding. Therefore, compared to using a compound, using a masterbatch resin composition involves more overall dispersion steps, making it easier to uniformly disperse the basic filler. From this viewpoint, it is preferable to use a masterbatch resin composition in a food packaging material manufacturing method. Furthermore, from the above viewpoint, food packaging materials molded using a masterbatch resin composition can be superior to those molded using a compound in terms of film-forming properties, smooth appearance characteristics, and freshness preservation performance. However, polyolefin resins have the problem of decomposing due to heat during extrusion processing, etc. In particular, when basic fillers are included in food packaging materials at high concentrations to improve freshness preservation performance, the deterioration of the polyolefin resin may be accelerated during pellet processing and / or molding of the food packaging material, which may adversely affect the processability of the pellets and / or the film-forming properties of the food packaging material. Furthermore, degradation of polyolefin resins can lead to discoloration of food packaging materials and the formation of blemishes during film formation, thus degrading the appearance of food packaging materials. These problems are particularly pronounced in masterbatch resin compositions containing higher concentrations of basic fillers, and therefore, improvements in the processability of masterbatch resin compositions are required.

[0008] This disclosure has been made in view of the circumstances described above, and in one embodiment, provides a food packaging material with excellent freshness preservation performance and appearance characteristics free from color change and blemishes. Furthermore, in another embodiment, provides a masterbatch resin composition and a thermoplastic resin composition for food packaging materials that have excellent processability and are used in the manufacture of the above food packaging material.

[0009] In order to solve the above problems, the inventors diligently conducted research and, as a result, discovered a masterbatch resin composition that can be suitably used to form food packaging materials, and thus completed the present invention.

[0010] That is, one embodiment of the present invention relates to a masterbatch resin composition for food packaging materials comprising a polyolefin resin (A), a basic filler (B), and an antioxidant (C), wherein the basic filler (B) has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, the antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, the content of the antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 3 to 50% by mass based on the total mass of the masterbatch resin composition. Another embodiment of the present invention relates to a thermoplastic resin composition for food packaging materials comprising the masterbatch resin composition for food packaging materials of the above embodiment and a main resin (D). Another embodiment of the present invention relates to a compound for food packaging materials comprising a polyolefin resin (A), a basic filler (B), and an antioxidant (C), wherein the basic filler (B) has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, the antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, the content of the antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 0.1 to 20% by mass based on the total mass of the compound. Another embodiment of the present invention relates to a food packaging material formed using the thermoplastic resin composition or compound for food packaging materials of the above embodiment. Another embodiment of the present invention relates to a method for producing a thermoplastic resin composition for food packaging materials, comprising the steps of melting and kneading the masterbatch resin composition for food packaging materials and the main resin (D) of the above embodiment.

[0011] According to one embodiment of this disclosure, a food packaging material with excellent freshness preservation performance and appearance characteristics can be provided. Furthermore, according to another embodiment, a masterbatch resin composition and a thermoplastic resin composition for food packaging materials with excellent processability can be provided for use in the manufacture of food packaging materials.

[0012] The embodiments of the present invention will be described in detail below, but the present invention is not limited to the embodiments described below. It goes without saying that other embodiments are also included in the scope of the present invention as long as they are consistent with the spirit of the present invention. Furthermore, numerical ranges specified using "~" in this specification include the numerical values ​​written before and after "~" as the lower and upper limits. In this specification, "film" and "sheet" are not distinguished by thickness. In other words, "sheet" in this specification includes thin film-like materials, and "film" in this specification includes thick sheet-like materials. In this specification, "masterbatch resin composition for food packaging materials" may also be written as "masterbatch resin composition," and "thermoplastic resin composition for food packaging materials" may also be written as "thermoplastic resin composition" or "resin composition." A masterbatch resin composition is a resin composition in which a high concentration of additives is dispersed in a resin, and which is mixed with the main resin at a specified ratio during the formation of a molded article to impart functionality to the plastic molded article. Unless otherwise noted, the various components described herein may be used independently, individually, or in combination of two or more. The numerical values ​​specified herein are those obtained by the methods disclosed in the embodiments or examples described later.

[0013] <Masterbatch Resin Composition for Food Packaging Materials> One embodiment of the present invention relates to a masterbatch resin composition for food packaging materials, wherein the masterbatch resin composition comprises a polyolefin resin (A), a basic filler (B), and an antioxidant (C), wherein the basic filler (B) has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, and the antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, the content of the antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 3 to 50% by mass based on the total mass of the masterbatch resin composition (100% by mass). The above configuration makes it possible to realize a masterbatch resin composition for food packaging materials that exhibits excellent processability even when containing a high concentration of basic filler, and furthermore, when used to form food packaging materials, provides excellent freshness preservation performance and color and appearance characteristics.

[0014] The masterbatch resin composition for food packaging materials of this embodiment will be described in detail below. (Polyolefin resin (A)) In this embodiment, polyolefin resin (A) is a polymer of olefin monomers such as ethylene, propylene, and butylene, and may be a block copolymer, a random copolymer, a bipolymer, or a terpolymer. Specifically, examples include polymers of α-olefins such as linear low-density polyethylene resin (LLDPE), low-density polyethylene resin (LDPE), high-density polyethylene resin (HDPE), and polypropylene resin (PP). From the viewpoint of moldability, polyolefin resin (A) preferably has a melt flow rate (MFR) value of 0.01 g / 10 min or more and 10 g / 10 min or less at 190°C and a 2.16 kg load. Here, MFR is the value measured at a heating temperature of 190°C and a 2.16 kg load in accordance with Annex A Table 1, Condition D of JIS K7210:1999, and the unit is g / 10 min.

[0015] Specific examples of polyolefin resin (A) include Suntec HD J300 (HDPE, manufactured by Asahi Kasei), Suntec LD F1810 (LDPE, manufactured by Asahi Kasei), Nipolon L F13 (LLDPE, manufactured by Tosoh Corporation), Novatec PP FA3EB (PP, manufactured by Nippon Polypropylene Co., Ltd.), and others.

[0016] The content of polyolefin resin (A) is preferably 20 to 96.99% by mass, and more preferably 49 to 95.0% by mass, based on the total mass of the masterbatch resin composition (100% by mass). From the viewpoint of extrusion processability of pellets and film-forming properties of food packaging materials, the lower limit of the polyolefin resin (A) content is preferably 20% by mass or more.

[0017] (Basic Filler (B)) Basic filler (B) is a basic filler with a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less. Basic filler (B) prevents fermentation and spoilage by bacteria and imparts a freshness-preserving function to molded bodies obtained from masterbatch resin compositions.

[0018] The basic filler (B) may have a pH of 10.0 to 13.0 in water. From the viewpoint of excellent processability and achieving both freshness preservation performance and appearance characteristics of food packaging materials, a pH of 11.0 to 12.5 is preferred. From the viewpoint of freshness preservation performance, a pH of 11.0 to 13.0, 12.0 to 13.0, or 12.5 to 13.0 is more preferred. From the viewpoint of moldability and appearance characteristics, a pH of 10.0 to 12.5 is more preferred. If the pH of the basic filler (B) becomes too high, there is a possibility of foreign matter generation or discoloration during the kneading of the thermoplastic resin composition, and it may also affect the moldability of the thermoplastic resin composition.

[0019] In this specification, the pH of the basic filler is the pH value measured at 23°C using a pH meter. A pH meter such as the Toa DKK HM-30P can be used. If the basic filler is soluble in water, the pH can be measured using an aqueous solution; if the basic filler is insoluble in water, the pH can be measured using the supernatant of the dispersion. Specifically, for example, 0.5 g of basic filler can be weighed, placed in a plastic container, 50 ml of deionized water can be added, the mixture can be vibrated for 30 minutes using a vibrator, then the solid-liquid can be separated using a centrifuge, the supernatant water can be temperature-stabilized in a 23°C bath, and the pH can be measured using a pH meter (Toa DKK HM-30P) to obtain the pH of the basic filler.

[0020] The basic filler (B) has a moisture content of 20,000 ppm or less, preferably 15,000 ppm or less, more preferably 10,000 ppm or less, even more preferably 5,000 ppm or less, and particularly preferably 2,000 ppm or less, from the viewpoint of appearance characteristics and moldability. The higher the moisture content, the stronger the basicity, which accelerates the deterioration of the resin and may lead to deterioration of moldability and discoloration. The moisture content can be reduced to 20,000 ppm or less by drying in an oven or the like. The oven temperature is preferably 80 to 100°C.

[0021] The water content of a basic filler can be determined by the Karl Fischer method. For example, by applying the Karl Fischer method in accordance with JIS K 0068:2001, the basic filler is heated, and Karl Fischer reagent is added dropwise to the generated water. The water content can then be calculated from the volume of reagent added up to the endpoint. As a water content meter, for example, a Karl Fischer trace water analyzer manufactured by Hiranuma Sangyo Co., Ltd. can be used. A 0.5 g sample is weighed out, the measurement temperature is set to 150°C, and the amount of water is quantified under vaporization conditions for 30 minutes to determine the water content.

[0022] The basic filler (B) is not particularly limited as long as it has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, and any generally available basic filler can be used. Examples include basic compounds containing alkali metals or alkaline earth metals, zeolites that release alkali metals or alkaline earth metal ions, or ion-releasing fillers, hydrotalcite, etc.

[0023] Basic compounds containing alkali metals or alkaline earth metals include carbonates, bicarbonates, silicates, phosphates, oxides, hydroxides, etc. Examples include sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium silicate, potassium silicate, calcium silicate, magnesium silicate, sodium phosphate, calcium oxide, calcium hydroxide, magnesium hydroxide, etc.

[0024] As zeolites that release alkali metal and alkaline earth metal ions, various natural or synthetic zeolites containing alkali metal and alkaline earth metal ions as exchangeable ions can be used.

[0025] Examples of ion-releasing fillers include oxide glasses such as aluminosilicate glass containing alkali metals or alkaline earth metals, borosilicate glass, and soda lime glass, as well as fluoride glasses such as zirconium fluoride glass.

[0026] In particular, basic compounds containing alkali metals or alkaline earth metals are preferred from the viewpoint of achieving both freshness preservation performance and appearance characteristics and moldability. The basic compound containing alkali metals or alkaline earth metals is more preferably a carbonate, oxide, or hydroxide, and even more preferably calcium oxide, calcium hydroxide, magnesium carbonate, calcium carbonate, or magnesium hydroxide. Particularly preferred are calcium oxide, calcium hydroxide, magnesium carbonate, or magnesium hydroxide.

[0027] The content of basic filler (B) is 3 to 50% by mass, more preferably 4 to 45% by mass, based on the total mass of the masterbatch resin composition (100% by mass). A content of 3% by mass or more easily enhances the freshness preservation effect of the food packaging material. Furthermore, a content of 50% by mass or less suppresses resin degradation and dispersion problems, provides excellent processability, reduces discoloration and blemishes, and easily provides food packaging material with a superior appearance.

[0028] From the viewpoint of appearance characteristics and moldability, the average particle diameter of the basic filler (B) is preferably 10.0 μm or less, more preferably 0.1 to 10.0 μm, and even more preferably 0.1 to 5.0 μm. In this specification, the average particle diameter of the basic filler (B) is determined by observing 100 particles randomly using a transmission electron microscope, measuring the distance between the two furthest points on the outer shape of each particle based on the length of the micron marker on the screen, and averaging the results.

[0029] (Antioxidant (C)) Antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants. By using a hindered amine antioxidant and / or a hydroxylamine antioxidant as antioxidant (C), excellent moldability can be easily obtained during pellet processing of the masterbatch resin composition and during molding of food packaging materials. Furthermore, by using a phosphorus antioxidant as antioxidant (C), even when a high concentration of basic filler is included, as in the masterbatch resin composition of this embodiment, discoloration due to oxidative degradation of the resin can be prevented, and excellent discoloration resistance can be easily obtained.

[0030] [Hindered Amine Antioxidants] Hindered amine antioxidants are derivatives of 2,2,6,6-tetramethylpiperidine, for example, 1-[2-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]ethyl]-4-[3-3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonic acid-bis-(1,2,2,6,6-pentamethyl-4-piperidyl), N,N',N'',N'''-tetrakis-(4,6-bis(butyl-(N-methyl-2,2,6,6-tetramethylpiperidine-4-yl)amino)-triazine-2-yl)-4,7-di Azadecane-1,10-amine, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate, (2,2,6,6-tetramethyl-4-piperidyl / tridecyl)-1,2,3,4-butanetetracarboxylate, (1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl)-1,2,3,4-butanetetracarboxylate, polycondensate of dibutylamine, 2,4,6-trichloro-1,3,5-triazine, N,N-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine, and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine. Polycondensate of dibutylamine-1,3,5-triazine-N,N-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine-N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, poly[{(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], polycondensate of 1,6-hexanediamine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl) and morpholin-2,4,6-trichloro-1,3,5-triazine, Poly[(6-morpholino-s-triazine-2,4-diyl)[(2,2,6,6-Tetramethyl-4-piperidyl)imino]-hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino], dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol copolymer, 1,2,3,4-butanetetracarboxylic acid and 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane mixed esterification product, poly[{6-[(1,1,3,3-tetramethylbutyl)amino]-S-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}-hexamethylene-{(2,2,6,6-tetramethyl-4-piperidyl)imino}], a mixture of tetramethylpiperidine fatty acid ester (50%) and polypropylene wax (50%), 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc. are mentioned.

[0031] Among the hindered amine antioxidants, from the viewpoint of imparting processing stability and long-term thermal stability to the thermoplastic resin composition, for example, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, dibutylamine·1,3,5-triazine·N,N-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine·N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine polycondensate, poly[{6-[(1,1,3,3-tetramethylbutyl)amino]-S-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}-hexamethylene-{(2,2,6,6-tetramethyl-4-piperidyl)imino}], a mixture of tetramethylpiperidine fatty acid ester (50%) and polypropylene wax (50%), 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc. are preferred.

[0032] [Hydroxylamine-based antioxidants] Examples of hydroxylamine-based antioxidants include N,N-dibenzylhydroxylamine, N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine, N,N-dilaurylhydroxylamine, N,N-didodecylhydroxylamine, N,N-ditetradecylhydroxylamine, and other N-di(C) １ ~C １５ Alkyl) hydroxylamine, N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine, N-hexadecyl-N-tetradecylhydroxylamine, N-hexadecyl-N-heptadecylhydroxylamine, N-hexadecyl-N-octadecylhydroxylamine, N-heptadecyl-N-octadecylhydroxylamine, N-methyl-N-octadecylhydroxylamine, etc. １６ ~C １８ Examples include alkyl)hydroxylamines. From the viewpoint of processability and appearance characteristics, N,N-di(C) １６ ~C １８ It is an alkyl hydroxylamine.

[0033] [Phosphorus-based antioxidants] Phosphorus-based antioxidants are organic compounds containing a phosphorus atom. Phosphorus-based antioxidants preferably contain a trivalent phosphorus atom, and more preferably are phosphite esters or phosphonic acid esters. Examples of phosphorus-based antioxidants include bis(2,4-di-t-butylphenyl)pentaerythrityl diphosphite, tetrakis(2,4-di-butylphenyl)-4,4'-biphenylene-diphosphonite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythrityl diphosphite, bis(2,4-di-t-butyl-6-methylphenyl)ethyl phosphite, tetrakis(2,4-di-butyl-5-methylphenyl)-4,4'-biphenylene-diphosphonite, bis(2,4-dicumylphenyl)pentaerythrityl diphosphite, 2,4,8,10-tetra-t-butyl-6-(2-ethylhexyloxy)-12H-dibenzo[d,g][1,3,2]dioxaphosphosine, and tris(2,4-di-t-butylphenyl) phosphite. or tris(mono or dinonylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite, 2,2'-methylenebis(4,6-di-t-butylphenyl)-2-ethylhexyl phosphite, cyclic neopentanetetraylbis(2,6-t-butyl-4-methylphenyl phosphite), bis(2,4-diquylphenyl) pentaerythritol diphosphite, 2,2',2''-nitrilo[triethyl-tris(3,3',5,5'-tetra-t-butyl-1,1'-biphenyl-2,2'-diyl)] phosphite, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenz[d. f][1.3.2]dioxaphosfepine, 2.10-dimethyl-4,8-di-t-butyl-6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-12H-dibenzo[d.g][1.3.2]dioxaphosphosine, 24.8,10-tetra-t-pentyl-6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-12-methyl-12H-dibenzo[d.g][1.3.2]dioxaphosphosine, 2.10-dimethyl-4,8-di-t-butyl-6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-12H-dibenzod[dg][1.3.2]dioxaphosphocin, 2,4,8,10-tetra-t-butyl-6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-dibenzod[dg][1,3.2]dioxaphosphepine, 2,10-dimethyl-4,8-di-t-butyl-6-(3,5-di-t-butyl-4-hydroxybenzoyloxy)-12H-dibenzod[dg][1.32]dioxaphosphocin, 2,4,8,10-tetra-t-butyl-6-(3,5-di-t-butyl-4-hydroxybenzoyloxy)-12-methyl-12H-dibenzod[dg][1.3.2]dioxaphosphocin, 2,10-dimethyl-4,8-di-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]-12H-dibenzod[dg][1.3.2]dioxaphosphocin, 2,4,8,10-tetra-t-butyl-6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-12H-dibenzod[dg][1.3.2]dioxaphosphocin, 2,4,8,10-tetra-t-butyl-6-[2,2-dimethyl-3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-dibenzod[df][1,3,2]dioxaphosphepine, etc. are mentioned.,

[0034] The masterbatch resin composition of this embodiment preferably contains one or more antioxidants (C) in a total content of 0.001 to 20% by mass, based on the total mass of the masterbatch resin composition (100% by mass). The above content is more preferably 0.01 to 10% by mass, even more preferably 0.01 to 5% by mass, and particularly preferably 0.05 to 3% by mass. When the antioxidant (C) content is within the above range, the extrudeability and film-forming properties can be improved. Furthermore, if the antioxidant (C) content is 0.001% by mass or more, the antioxidant effect is further improved, and deterioration of the polyolefin resin and antioxidant, and yellowing, can be easily suppressed. If the antioxidant (C) content is 20% by mass or less, the cause of breakage during film formation is suppressed, and the dispersibility in the composition is improved, so the cause of appearance defects such as the occurrence of blemishes in inflation films can be easily suppressed.

[0035] The content of antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of basic filler (B). From the viewpoint of moldability and hue, 0.4 parts by mass or more is preferred, and 0.5 parts by mass or more is more preferred. From the viewpoint of moldability and film material, 400 parts by mass or less is preferred, 300 parts by mass or less is more preferred, 200 parts by mass or less is more preferred, 100 parts by mass or less is more preferred, 50 parts by mass or less is more preferred, and 10 parts by mass or less is even more preferred.

[0036] (Other Components) The masterbatch resin composition may optionally contain other components such as additives. Examples of additives include antioxidants other than antioxidant (C), dispersants, lubricants (higher fatty acid metal salts, waxes, etc.), surfactants, antistatic agents, flame retardants, UV absorbers, fillers, and pigments. The selection of other optional components and their amounts are not particularly limited as long as the problem can be solved. Multiple additives may be used in combination. Furthermore, the masterbatch resin composition may partially contain resins other than polyolefin resin (A) as long as it does not hinder the effects of this embodiment.

[0037] Masterbatch resin compositions can be colored with pigments to produce molded articles with excellent heat-shielding properties or easily identifiable molded articles. The pigments are not particularly limited and can be those that are generally available, but from the viewpoint of the natural environment, it is preferable that they are substantially free of pigments containing cadmium, lead, chromium, arsenic, mercury, copper, selenium, nickel, molybdenum, and fluorine.

[0038] For example, when a masterbatch resin composition contains a pigment, it is preferable to use a dispersant to disperse the pigment, and examples of dispersants include fatty acid metal salts. The fatty acid component of the fatty acid metal salt is preferably a chain-like carboxylic acid having 6 to 30 carbon atoms, and may be linear or branched, and may have only saturated bonds or only unsaturated bonds. Examples of fatty acids include caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, behenic acid, oleic acid, erucic acid, linoleic acid, montanic acid, etc. As for the metal, elements from Group 1, Group 2, Group 12, and Group 13 are preferred, and elements from Group 1 or Group 2 are more preferred. Specific examples include sodium, potassium, calcium, magnesium, and barium.

[0039] Examples of fatty acid metal salts include calcium stearate, magnesium stearate, barium stearate, calcium laurate, magnesium laurate, and sodium montanoate. One of these may be used, or two or more may be used in combination. Among these, calcium stearate, magnesium stearate, calcium laurate, and magnesium laurate are preferred.

[0040] (Method for Producing Masterbatch Resin Composition) The method for producing the masterbatch resin composition of this embodiment is not particularly limited. For example, it can be produced by kneading a polyolefin resin (A), a basic filler (B), and an antioxidant (C) at a temperature at which the polyolefin resin (A) melts. Specifically, for example, a masterbatch resin composition can be obtained in pellet, powder, granular, or bead form by mixing and melt-kneading a polyolefin resin (A), a basic filler (B), an antioxidant (C), and various additives as needed, using a batch kneader, single-screw extruder, twin-screw extruder, rotor-type twin-screw kneader, etc. Examples of the batch kneader include a kneader, roll mill, super mixer, high-speed mixer, ball mill, sand mill, attritor, and Banbury mixer. It is preferable to use a single-screw extruder or twin-screw extruder to produce a pellet-shaped masterbatch resin composition because it has strong kneading power and facilitates subsequent molding.

[0041] <Thermoplastic Resin Composition for Food Packaging Materials> The thermoplastic resin composition for food packaging materials of this embodiment comprises a polyolefin resin (A), a basic filler (B), and an antioxidant (C). From the viewpoint of freshness preservation performance, the content of the basic filler (B) is preferably 0.1 to 20% by mass, and more preferably 0.5 to 20% by mass, based on the total mass of the thermoplastic resin composition for food packaging materials (100% by mass). In one embodiment, the thermoplastic resin composition may be obtained by melt-kneading a masterbatch resin composition and a main resin (D). In another embodiment, the thermoplastic resin composition may be obtained by melt-kneading a polyolefin resin (A), a basic filler (B), and an antioxidant (C) without going through a masterbatch resin composition (compound). In the case of a compound, the polyolefin resin (A) becomes the main resin of the thermoplastic resin composition. Therefore, it is preferable to adjust the amount of polyolefin resin (A) added so that the content of the basic filler (B) falls within the above range.

[0042] In other words, the compound comprises a basic filler (B) having a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, and an antioxidant (C) being at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, with an antioxidant content of 0.1 to 450 parts by mass per 100 parts by mass of basic filler (B), and the content of basic filler (B) may be 0.1 to 20% by mass based on the total mass of the compound (100% by mass). From the viewpoint of freshness preservation performance, the content of basic filler (B) is more preferably 0.5 to 20% by mass.

[0043] Typically, masterbatches involve dispersion processes in two stages: during manufacturing and during molding. Therefore, compared to compounds, masterbatch manufacturing involves more overall dispersion processes, making it easier to uniformly disperse the basic filler (B). From this perspective, it is preferable to use a masterbatch resin composition to form food packaging materials. Furthermore, from the above perspective, food packaging materials molded using a masterbatch resin composition can be superior in terms of film-forming properties, smooth appearance, and freshness preservation performance compared to those using a compound. Moreover, while stronger shear kneading is desirable when manufacturing compounds from the viewpoint of dispersibility, strong shear kneading when incorporating high concentrations of basic fillers into food packaging materials may accelerate the degradation of polyolefin resins. For this reason, it is preferable to use a masterbatch resin composition.

[0044] Therefore, in some embodiments, the method for producing a thermoplastic resin composition for food packaging materials preferably includes a step (1) of melt-kneading a masterbatch resin composition and a main resin (D). In the above production method, a step (0) of preparing a masterbatch resin composition may be provided prior to step (1). In step (0), a masterbatch resin composition may be obtained by melt-kneading a high concentration of basic filler (B), and then the main resin (D) may be further added and the melt-kneading of step (1) may be carried out. This is preferable because by going through a step of melt-kneading while gradually decreasing the concentration of basic filler (B), the basic filler (B) can be made uniform in the masterbatch resin composition and stably dispersed.

[0045] The thermoplastic resin composition can be obtained in the form of pellets, powder, granules, or beads, for example, with pellets or powder being preferred, and pellets being more preferred.

[0046] Mixing equipment for producing thermoplastic resin compositions may include, for example, a kneader, roll mill, high-speed mixer, ball mill, sand mill, attritor, or batch kneader such as a Banbury mixer, a single-screw extruder, a twin-screw extruder, a rotor-type twin-screw kneader, etc., and the raw materials can be mixed and melt-kneaded to produce a resin composition in the form of pellets, powders, granules, or beads. In this embodiment, from the viewpoint of producing a uniform dispersion, it is preferable to form the composition into pellets using a single-screw extruder or a twin-screw extruder.

[0047] When producing a thermoplastic resin composition using a masterbatch resin composition, the process includes a step of melt-kneading the masterbatch resin composition and the main resin (D). From the viewpoint of achieving both freshness preservation performance, appearance characteristics, and moldability, the amount of masterbatch resin composition blended is preferably 0.1 to 50 parts by mass, and more preferably 0.2 to 45 parts by mass, per 100 parts by mass of the main resin (D). From the viewpoint of freshness preservation performance, the above blending amount is more preferably 0.3 to 45 parts by mass.

[0048] (Main resin (D)) In this embodiment, the main resin (D) is a resin that forms the base of the thermoplastic resin composition and is used by mixing it with the masterbatch resin composition during molding. The main resin (D) can be any conventionally known thermoplastic resin, but it is preferably a polyolefin resin. The polyolefin resin can be the same as the polyolefin resin (A) described above. Specifically, examples include polymers of α-olefins such as linear low-density polyethylene resin (LLDPE), low-density polyethylene resin (LDPE), high-density polyethylene resin (HDPE), and polypropylene resin (PP). The main resin (D) does not have to be the same resin as the polyolefin resin (A) used in the masterbatch resin composition, but from the viewpoint of compatibility, it is preferable that it be the same type of polyolefin resin. That is, if the polyolefin resin (A) is HDPE, it is preferable that the main resin (D) is also HDPE.

[0049] <Food Packaging Material> The food packaging material is a molded article formed using the thermoplastic resin composition for food packaging material of this embodiment. That is, the method for manufacturing the food packaging material comprises a step of molding the thermoplastic resin composition for food packaging material of this embodiment into a predetermined form. The above manufacturing method may further include, if necessary, a step of preparing the thermoplastic resin composition for food packaging material and a step of preparing a masterbatch resin composition to be used in the thermoplastic resin composition for food packaging material. These steps can be carried out according to the method described above. The form of the food packaging material is not particularly limited, but examples include film (sheet), tube, bag, plate, three-dimensional structure, etc. For example, if the packaging material is in the form of a bag, it may be a packaging material directly formed from the thermoplastic resin composition, or it may be a packaging material obtained by further processing a molded article that has been processed from the thermoplastic resin composition into a film or tube, etc. The method for further processing a molded article, such as a film or tube, formed from the above thermoplastic resin composition into a bag shape is not particularly limited, but examples include heat sealing with a heat sealer, bonding with welding adhesive, and processing with a bag-making machine such as a pillow pack, stretch pack, or blister pack.

[0050] When food packaging materials are to be made into films, the above thermoplastic resin composition can be formed into films by known film molding methods. For example, the inflation method (circular die method) and the T-die method, which are melt extrusion methods, can be used. Other methods such as casting, calendering, and pressing may also be used. Furthermore, the obtained film may be further stretched uniaxially or biaxially to improve transparency and strength. When forming a film, it does not necessarily have to be a single-layer film, but a laminated film (multilayer film) may be made by laminating two or more films made of the above resin.

[0051] Furthermore, in the case of film-like food packaging materials, the thickness of the film is not particularly limited, but is usually 5 to 200 μm, preferably 10 to 60 μm, and more preferably about 20 to 40 μm.

[0052] Furthermore, when food packaging materials are to be in the shape of containers such as bottles, the thermoplastic resin composition can be processed into any container shape such as bottles or trays by molding means such as blow molding, injection molding, or vacuum molding.

[0053] Furthermore, if the food packaging material is a film or similar, in addition to being a bag-shaped food packaging material that contains the food itself as described above, it is also possible to use a food packaging material in which the food is placed in a container such as a tray, and the top or opening of this container is covered with the film to seal it.

[0054] From the viewpoint of freshness preservation performance, the content of basic filler (B) is preferably 0.1 to 20% by mass, and more preferably 0.5 to 20% by mass, based on the total mass of the food packaging material (100% by mass).

[0055] The following are examples of typical embodiments of the present invention. However, the present invention is not limited to the following examples and includes various embodiments. <1> A masterbatch resin composition comprising a polyolefin resin (A), a basic filler (B), and an antioxidant (C), wherein the basic filler (B) has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, the antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, the content of the antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 3 to 50% by mass based on 100% by mass of the masterbatch resin composition, a masterbatch resin composition for food packaging materials. <2> The masterbatch resin composition for food packaging materials according to <1>, wherein the basic filler (B) is at least one selected from the group consisting of calcium oxide, calcium hydroxide, magnesium carbonate, and magnesium hydroxide. <3> The masterbatch resin composition for food packaging materials according to <1> or <2>, wherein the average particle size of the basic filler (B) is 10.0 μm or less. <4> The masterbatch resin composition for food packaging materials according to any one of <1> to <3>, wherein the content of the antioxidant (C) is 0.01 to 5% by mass, based on 100% by mass of the masterbatch resin composition. <5> A thermoplastic resin composition for food packaging materials comprising the masterbatch resin composition for food packaging materials according to any one of <1> to <4>, and a main resin (D). <6> The thermoplastic resin composition for food packaging materials according to <5> above, wherein the content of the basic filler (B) is 0.1 to 20% by mass, based on the total mass of the thermoplastic resin composition for food packaging materials (100% by mass).<7> A compound for food packaging materials comprising a polyolefin resin (A), a basic filler (B), and an antioxidant (C), wherein the basic filler (B) has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, the antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, the content of the antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 0.1 to 20% by mass based on 100% by mass of the compound. <8> A food packaging material formed from the thermoplastic resin composition for food packaging materials described in <5> or <6> above, or the compound described in <7> above. <8> A method for producing a thermoplastic resin composition for food packaging materials, comprising the steps of melting and kneading a masterbatch resin composition for food packaging materials described in any one of <1> to <4> above, and a main resin (D).

[0056] This disclosure relates to the subject matter described in Japanese Patent Application No. 2024-227806, filed on 24 December 2024, and Japanese Patent Application No. 2025-140151, filed on 26 August 2025, all of which are incorporated herein by reference.

[0057] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass," respectively, and "RH" means relative humidity. A blank space in the table indicates that there is no formulation.

[0058] The following is the method for measuring the pH, moisture content, and average particle size of the basic filler. <pH measurement> 0.5 g of basic filler was weighed and placed in a plastic container, 50 ml of deionized water was added, and the mixture was vibrated with a vibrator for 30 minutes. After separating the solid and liquid using a centrifuge, the supernatant water was stabilized in a 23°C constant temperature bath, and the pH was measured with a pH meter (HM-30P pH meter manufactured by Toa DKK Co., Ltd.).

[0059] <Moisture content of basic filler> 0.5 g of the sample was weighed out, and the moisture content was measured using the Karl Fischer method with a Karl Fischer trace moisture analyzer manufactured by Hiranuma Sangyo Co., Ltd., under vaporization conditions of 30 minutes at a measurement temperature of 150°C.

[0060] <Method for measuring the average particle size of basic fillers> Basic fillers were observed using a JEOL transmission electron microscope JEM-1010. 100 particles were randomly observed, and the distance between the two furthest points on the outer shape of each particle was measured based on the length of the micron marker on the screen. The average particle size was then calculated.

[0061] The materials used in the examples and comparative examples are listed below. (Polyolefin resin (A)) (A-1): Novatec PP FA3EB (PP) (A-2): Suntec LD F1810 (LDPE) (A-3): Suntec HD J300 (HDPE) (A-4): Nipolon L F13 (L-LDPE)

[0062] (Basic filler (B), etc.) (B-1): Calcium hydroxide from Production Example 1, pH 12.5, moisture content 2,000 ppm, average particle size: 4.9 μm (B-2): Calcium oxide from Production Example 2, pH 12.5, moisture content 4,000 ppm, average particle size: 5.0 μm (B-3): Calcium oxide from Production Example 3, pH 12.5, moisture content 18,000 ppm, average particle size: 30.0 μm (B-4): Magnesium carbonate from Production Example 4, pH 10.0, moisture content 2,000 ppm, average particle size: 3.0 μm (B-5): Calcium carbonate from Production Example 5, pH 12.5, moisture content 2,000 ppm, average particle size: 4.9 μm (B-6): Calcium hydroxide from Production Example 6, pH 12.5, moisture content 5,000 ppm, average particle size: 3.0 μm (B-7): Calcium hydroxide from Production Example 7, pH 12.5, moisture content 10,000 ppm, average particle size: 4.0 μm (B'-1): Calcium carbonate, KS-1300 (manufactured by Calfine Co., Ltd., pH 9.0, moisture content 10,000 ppm, average particle size: 3.2 μm) (B'-2): Barium hydroxide (manufactured by Nippon Chemical Industrial Co., Ltd., pH 14.0, moisture content 9,000 ppm, average particle size: 5.0 μm) (B'-3): Calcium hydroxide, M-300 (manufactured by Inoue Mitsuyoshi Shoten Co., Ltd., pH 12.5, moisture content 25,000 ppm, average particle size: 4.9 μm)

[0063] <Method for producing basic filler (B)> (Production example 1: Basic filler (B-1)) M-300 (calcium hydroxide, manufactured by Inoue Mitsuyoshi Shoten Co., Ltd.) was dried in a vacuum oven at a temperature of 100°C and a pressure of 300 Pa for 24 hours to produce dried basic filler (B-1).

[0064] (Manufacturing Example 2: Basic Filler (B-2)) F-Lime-1300K (calcium oxide, manufactured by Calfine Co., Ltd.) was dried in a vacuum oven at a temperature of 100°C and a pressure of 300 Pa for 24 hours to produce dried basic filler (B-2).

[0065] (Manufacturing Example 3: Basic Filler (B-3)) F-Lime-100 (calcium oxide, manufactured by Calfine Co., Ltd.) was dried in a vacuum oven at a temperature of 100°C and a pressure of 300 Pa for 24 hours to produce dried basic filler (B-3).

[0066] (Manufacturing Example 4: Basic Filler (B-4)) Magnesium carbonate (Kinsei) (manufactured by Kamishima Chemical Industry Co., Ltd.) was dried in a vacuum oven at a temperature of 100°C and a pressure of 300 Pa for 24 hours to produce dried basic filler (B-4).

[0067] (Manufacturing Example 5: Basic Filler (B-5)) Calcium carbonate (manufactured by Calfine Co., Ltd.) was dried in a vacuum oven at a temperature of 100°C and a pressure of 300 Pa for 24 hours to produce dried basic filler (B-5).

[0068] (Manufacturing Example 6: Basic Filler (B-6)) M-300 (calcium hydroxide, manufactured by Inoue Mitsuyoshi Shoten Co., Ltd.) was dried in a vacuum oven at a temperature of 80°C and a pressure of 300 Pa for 10 hours to produce dried basic filler (B-6).

[0069] (Manufacturing Example 7: Basic Filler (B-7)) M-300 (calcium hydroxide, manufactured by Inoue Mitsuyoshi Shoten Co., Ltd.) was dried in a vacuum oven at a temperature of 80°C and a pressure of 300 Pa for 5 hours to produce dried basic filler (B-7).

[0070] (Antioxidant (C)) (C-1): Chimassorb 944 (manufactured by BASF Japan Ltd., hindered amine antioxidant) poly[{6-[(1,1,3,3-tetramethylbutyl)amino]-S-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}-hexamethylene-{(2,2,6,6-tetramethyl-4-piperidyl)imino}]) (C-2): Irgastab FS 042 (manufactured by BASF Japan Ltd., hydroxylamine antioxidant) N,N-dioctadecylhydroxylamine (C-3): Irgafos 38 (manufactured by BASF Japan Ltd., phosphorus antioxidant) bis(2,4-di-t-butyl-6-methylphenyl)ethyl phosphine (C-4): Phosphorus-based antioxidant of Production Example 8 (2,10-dimethyl-4,8-di-t-butyl-6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-12H-dibenzo[d.g][1.3.2]dioxaphosphosine)

[0071] <Method for producing antioxidant (C)> (Production example 8: Production of antioxidant (C-4)) In a flask equipped with a thermometer, a stirrer, and a condenser, 10.2 parts of 2,2'-methylenebis(6-t-butyl-4-methylphenol) and 110 parts of toluene were added under a nitrogen stream. Then, 4.1 parts of phosphorus trichloride were added under stirring, followed by 6.7 parts of triethylamine, and the mixture was kept warm at 80°C for 8 hours. After cooling to room temperature, 50 parts of toluene and 8.33 parts of 3-(3,5-di-t-butyl-4-hydroxyphenyl)propanol were added, followed by 3.3 parts of triethylamine, and the mixture was kept warm at 80°C for 7 hours. Next, after cooling to room temperature, the resulting triethylamine hydrochloride was filtered and washed. After concentrating the filtered liquid, the residue was purified by silica gel chromatography to obtain 4.6 parts of a white crystalline phosphorus-based antioxidant.

[0072] (Other antioxidants) (C'-1): Adekastab AO-20 (manufactured by ADEKA Corporation, phenolic antioxidant) (C'-2): Adekastab LA-24 (manufactured by ADEKA Corporation, benzotriazole antioxidant)

[0073] (Main resin (D)) (D-1): Novatec PP FA3EB (PP) (D-2): Suntec LD F1810 (LDPE) (D-3): Suntec HD J300 (HDPE) (D-4): Nipolon L F13 (L-LDPE)

[0074] (Example 1) [Production of Masterbatch Resin Composition for Food Packaging Materials] A masterbatch resin composition for food packaging materials (M-1) was obtained by mixing polyolefin resin (A) at a ratio of 96.995% by mass, basic filler (B) at a ratio of 3% by mass, and antioxidant (C) at a ratio of 0.005% by mass. The mixture was extruded at 200°C using a twin-screw extruder (manufactured by Japan Steel Works, Ltd.) and granulated. The antioxidant (C-1) content was 0.2 parts by mass per 100 parts by mass of basic filler (B-1).

[0075] (Examples 2-40, Comparative Examples 1-6) Except for changing the composition and blending ratio (mass%) of Example 1 as shown in Table 1, pellet-shaped masterbatch resin compositions for food packaging materials (M-2 to 40, M-41 to 45) were produced in the same manner as in Example 1. Note that M-46 in Comparative Example 6 had poor extrusion processability and it was not possible to produce a pellet-shaped masterbatch resin composition for food packaging materials. Therefore, in Comparative Example 6, film-forming performance evaluation, yellowness (YI value) evaluation, film particle count evaluation, and freshness retention performance evaluation could not be performed.

[0076] (Example 41) [Production of thermoplastic resin composition for food packaging materials] Polyolefin resin (A) was mixed in an amount of 96.7% by mass of polyolefin resin (A-1), basic filler (B) in an amount of 3% by mass of basic filler (B-1), and antioxidant (C) in an amount of 0.3% by mass of antioxidant (C-3). The mixture was extruded at 200°C using a twin-screw extruder (manufactured by Japan Steel Works, Ltd.) and granulated to obtain thermoplastic resin composition 1 (compound). The antioxidant (C-3) content was 10 parts by mass per 100 parts by mass of basic filler (B-1).

[0077] [Manufacturing of food packaging material] The obtained thermoplastic resin composition (1) was used to produce a film-like food packaging material with a folded width of 450 mm and an average thickness of 50 μm using an inflation molding machine (manufactured by Hokushin Sangyo Co., Ltd.).

[0078] (Examples 42-44, Comparative Example 7) Except for changing the composition and blending ratio (mass%) of Example 41 as shown in Table 3, thermoplastic resin compositions 2-4 and 48, which are compounds, were manufactured in the same manner as in Example 41. Subsequently, a film-like food packaging material was manufactured in the same manner as in Example 41. Note that thermoplastic resin composition 48 of Comparative Example 7 had poor film-forming properties and could not be used to manufacture a film-like food packaging material. Therefore, in Comparative Example 7, yellowness (YI value) evaluation, film piece count evaluation, and freshness retention performance evaluation could not be performed.

[0079] (Example 45) The obtained masterbatch resin composition for food packaging materials (M-1) was placed in a super mixer (manufactured by Kawata Co., Ltd.) at a temperature of 20°C for 5 minutes, and then melt-kneaded in a twin-screw extruder (manufactured by Nippon Placon Co., Ltd.) set to a temperature of 200°C to obtain a pelletized thermoplastic resin composition 5 for food packaging materials.

[0080] [Manufacturing of Food Packaging Material] The obtained pelletized thermoplastic resin composition for food packaging material was used to produce a film-like food packaging material with a folded width of 450 mm and an average thickness of 50 μm using an inflation molding machine (manufactured by Hokushin Sangyo Co., Ltd.).

[0081] (Examples 46-87, Comparative Examples 8-12) Except for changing the composition and blending ratio (mass%) of Example 45 as shown in Table 3, pellet-shaped thermoplastic resin compositions 6-47 and 49-53 for food packaging were prepared in the same manner as in Example 45. Subsequently, film-shaped food packaging materials were prepared in the same manner as in Example 45. Note that the thermoplastic resin compositions 50, 51, and 53 for food packaging materials in Comparative Examples 9, 10, and 12 had poor film-forming properties and could not be used to produce film-shaped food packaging materials. Therefore, yellowness (YI value) evaluation, film piece count evaluation, and freshness retention performance evaluation could not be performed in Comparative Examples 9, 10, and 12.

[0082]

[0083]

[0084]

[0085]

[0086]

[0087] 《Evaluation of Masterbatch Resin Composition, Thermoplastic Resin Composition, and Food Packaging Material》 The masterbatch resin composition, thermoplastic resin composition, and food packaging material of this embodiment were evaluated as follows. The obtained masterbatch resin composition or compound was evaluated for "extrusion processability". Furthermore, the film-like food packaging material molded using the obtained masterbatch resin composition or compound for food packaging material was evaluated for "film-forming ability", "yellowness (YI value)", "number of film particles", and "freshness preservation performance". Details of the evaluation method are as follows, and the evaluation results are shown in Table 3. The evaluation criteria are as follows, with "++++", "+++", "++", and "+" considered to be usable, and "NG" considered to be unusable.

[0088] <Extrusion Processability Evaluation> When the masterbatch resin compositions or compounds for food packaging materials, such as those in the examples, were produced continuously for one hour using a twin-screw extruder, strand breakage was checked and the productivity (processability) was evaluated according to the following criteria. Strand breakage refers to the breakage of the strand, making it impossible to extrude the strand. [Evaluation Criteria] +++: No strand breakage occurs. ++: Strand breakage occurs 1 or more times but less than 5 times. +: Strand breakage occurs 5 or more times but less than 10 times. NG: Strand breakage occurs 10 or more times, or pellets cannot be produced.

[0089] <Evaluation of Film-Making Properties> The film-making properties of the obtained film-like food packaging material were evaluated as follows. The maximum take-up speed at which the balloon can be stably inflated while maintaining a fold width of 400 mm and an average thickness of 30 μm of the inflation film was measured, and the variation in fold width and the presence or absence of holes during measurement were checked. The width of the double film when the balloon-shaped molded film extruded from the die is folded into a double film by passing it through a cooling roll is called the fold width. A large variation in the fold width indicates a large variation in thickness, making it difficult to maintain a cylindrical shape. In other words, it becomes difficult to stably form a balloon. In addition, holes in the manufactured film are considered defects and are evaluated as poor quality. Therefore, the presence of holes in the film, the maximum take-up speed, and the variation in fold width within a length of 20 m of the obtained film were evaluated. [Evaluation Criteria] ++++: No holes occur in the film, the maximum take-up speed is 15 m / min or more, and the variation in fold width is less than 10 mm. +++: No holes were made in the film, the maximum take-up speed was 10 m / min or more but less than 15 m / min, and the variation in fold width was less than 20 mm, or the maximum take-up speed was 15 m / min or more, and the variation in fold width was 10 mm or more but less than 20 mm. ++: No holes were made in the film, but the maximum take-up speed was 10 m / min or more, and the variation in fold width was 20 mm or more, or the maximum take-up speed was less than 10 m / min, and the variation in fold width was less than 20 mm. +: No holes were made in the film, but the maximum take-up speed was less than 10 m / min, and the variation in fold width was 20 mm or more. NG: Holes were made in the film.

[0090] <Yellowness (YI value) evaluation> For the obtained film-like food packaging material, using the image spectro-colorimeter AU Color COLOR7x manufactured by KURABO INDUSTRIES LTD., the L value (lightness), a value, and b value of the test piece were measured under a D - 65(10) standard light source, and the YI value was calculated according to JIS K7373:2006 to measure the yellowness. It can be said that the smaller the YI value, the more the yellowing is suppressed. [Evaluation criteria] ++++: 0 ≤ YI < 3 +++: 3 ≤ YI < 5 ++: 5 ≤ YI < 10 +: 10 ≤ YI < 20 NG: 20 ≤ YI

[0091] <Film defect number evaluation> For the obtained film-like food packaging material, the surface of the film was observed visually, and the size of the defects and the number of defects of that size per 100 cm ２ of the film were counted and evaluated. The size of the above-mentioned defects means the value measured by directly comparing visually (with the naked eye) using the "Miscellaneous Goods Measurement Chart" manufactured by the Printing Bureau of the Ministry of Finance as a reference. [Evaluation criteria] +++: No defects of size 0.03 mm ２ or more. ++: There are defects of size 0.03 mm ２ or more, but no defects of size 0.05 mm ２ or more. +: There are defects of size 0.05 mm ２ or more, but no defects of size 0.1 mm ２ or more. NG: There is 1 or more defect of size 0.1 mm ２ or more.

[0092] <Freshness retention performance evaluation> Food was put into the obtained film-like food packaging material, sealed by heat sealing, and then left for 3 days in an environment of 30°C and 85% RH. The freshness retention performance was evaluated from the change in color value after leaving. The detailed method is shown below.

[0093] First, cut a flower bud (about 5 cm) from a commercially available cauliflower, and measure the L ＊ value and b ＊ value of the top of the flower bud using a colorimeter (Color Reader CR - 20 manufactured by Konica Minolta). The color L ＊ value and b ＊The value was measured three times, and the average value was used. Next, color L ＊ value, b ＊ The cauliflower whose color was measured was placed in food packaging. Next, the food packaging containing the sealed cauliflower was placed in a constant temperature and humidity chamber (ESPEC LHU124) set to 30°C and 85% RH, and left for three days. Afterward, the cauliflower was removed from the container and its color value was measured. The method for measuring the color value was the same as before the cauliflower was left to stand. Color L ＊ value, b ＊ For each value, the change in color value after leaving it unattended was calculated using the following formula: Formula: Change in color value = (Color value after leaving it unattended) - (Color value before leaving it unattended)

[0094] The freshness preservation performance was evaluated based on changes in color value according to the following criteria. [Evaluation Criteria] +++: Color L ＊ value, b ＊ Value change is 3 or less for both ++: Color L ＊ value, b ＊ The change in both values ​​is greater than 3 and less than or equal to 5. +: Color L ＊ value, b ＊ If any one of the values ​​changes to a value greater than 5, NG: Color L ＊ value, b ＊ The change in value is greater than 5 for both.

[0095]

[0096]

[0097]

[0098] As shown in Table 3, the masterbatch resin composition and thermoplastic resin composition for food packaging materials of the present invention exhibit excellent processability. Furthermore, it was confirmed that food packaging materials formed using these masterbatch resin compositions or thermoplastic resin compositions exhibit excellent freshness preservation performance and appearance characteristics.

Claims

1. A masterbatch resin composition comprising a polyolefin resin (A), a basic filler (B), and an antioxidant (C), wherein the basic filler (B) has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, the antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, the content of the antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 3 to 50% by mass based on the total mass of the masterbatch resin composition, a masterbatch resin composition for food packaging materials.

2. The masterbatch resin composition for food packaging materials according to claim 1, wherein the basic filler (B) is at least one selected from the group consisting of calcium oxide, calcium hydroxide, magnesium carbonate, and magnesium hydroxide.

3. The masterbatch resin composition for food packaging materials according to claim 1 or 2, wherein the average particle size of the basic filler (B) is 10.0 μm or less.

4. The masterbatch resin composition for food packaging materials according to any one of claims 1 to 3, wherein the content of the antioxidant (C) is 0.01 to 5% by mass based on the total mass of the masterbatch resin composition.

5. A masterbatch resin composition for food packaging materials according to any one of claims 1 to 4, comprising a polyolefin resin (A), a basic filler (B), and an antioxidant (C), and a thermoplastic resin composition for food packaging materials comprising a main resin (D).

6. The thermoplastic resin composition for food packaging materials according to claim 5, wherein the content of the basic filler (B) is 0.1 to 20% by mass, based on 100% by mass of the thermoplastic resin composition for food packaging materials.

7. A compound for food packaging materials comprising a polyolefin resin (A), a basic filler (B), and an antioxidant (C), wherein the basic filler (B) has a pH of 10.0 to 13.0 in water and a water content of 20,000 ppm or less, the antioxidant (C) is at least one selected from the group consisting of hindered amine antioxidants, hydroxylamine antioxidants, and phosphorus antioxidants, the content of the antioxidant (C) is 0.1 to 450 parts by mass per 100 parts by mass of the basic filler (B), and the content of the basic filler (B) is 0.1 to 20% by mass based on the total mass of the compound.

8. A food packaging material formed using the thermoplastic resin composition for food packaging materials described in claim 5 or the compound described in claim 7.

9. A method for producing a thermoplastic resin composition for food packaging materials, comprising the steps of melting and kneading a masterbatch resin composition for food packaging materials according to any one of claims 1 to 4, and a main resin (D).

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