JP7707525B2 - MASTERBATCH, AROMATIC POLYESTER RESIN COMPOSITION, MOLDED ARTICLE AND METHOD FOR PRODUCTION THEREOF - Google Patents

Description

The present invention relates to a masterbatch containing polybutylene terephthalate (hereinafter also referred to as "PBT"), a resin composition containing an aromatic polyester, a molded article, and a method for producing the same. More specifically, the present invention relates to a method for producing an aromatic polyester resin composition for films, a masterbatch used therein and a method for producing the same, and a method for producing a film using the aromatic polyester resin composition for films.

PBT resin is widely used for a variety of purposes due to its excellent properties, including ease of molding, mechanical properties, heat resistance, and chemical resistance. In recent years, it has also begun to be used for films and sheets, taking advantage of its gas barrier properties.

However, this film has low slipperiness, and when rolled up, the film sticks to itself, making it difficult to pull out, and there are problems with scratches and wrinkles forming when the film is pulled out forcefully.

For this reason, a method has been adopted in which fine particles are added to form unevenness on the film surface and increase the slipperiness of the film (see Reference 1). However, the use of fine particles tends to increase the tendency for poor dispersion to occur, particularly in the master batch where the fine particles are at a high concentration, which not only leads to the occurrence of film defects and an increase in filter pressure during film production, but also accelerates resin degradation, making stable film production difficult.

JP 2019-81825 A

The problem that the present invention aims to solve is to provide a film made of an aromatic polyester resin composition containing at least PBT resin, which suppresses the occurrence of film defects, suppresses filter pressure rise when forming a film from the resin composition, and further suppresses the progression of resin deterioration, enabling stable film formation, and to provide a method for producing the aromatic polyester resin composition and film, as well as a masterbatch and a method for producing the same that can provide such an aromatic polyester resin composition for film.

In order to solve the above problems, the inventors conducted extensive research and discovered that by optimizing the viscosity of the masterbatch PBT resin, particle aggregation, which is a defect in films produced using the masterbatch, can be eliminated and resin deterioration, which causes poor film formability, can be suppressed, thereby solving the present invention.

That is, the present invention provides the following inventions.
[1] The present invention relates to a master batch (1) characterized by containing, per 100 parts by mass of a polybutylene terephthalate resin (a) having an intrinsic viscosity of 0.5 or more and less than 0.9, less than 15 parts by mass of fine particles (b) having an average particle size of 0.5 to 10 μm.

[2] The present invention also relates to a method for producing a masterbatch, which comprises a step of blending and melt-kneading 100 parts by mass of polybutylene terephthalate resin (a) having an intrinsic viscosity of 0.5 or more and less than 0.9 with less than 15 parts by mass of fine particles (b) having an average particle size of 0.5 to 10 μm.

[3] The present invention further provides a method for producing a polybutylene terephthalate resin composition exclusively used for films, comprising:
The present invention relates to a method for producing an aromatic polyester polybutylene terephthalate resin composition, comprising the step of blending an aromatic polyester polybutylene terephthalate resin (c) with the masterbatch according to [1] and melt-kneading the blend.

[4] The present invention further relates to a method for producing a film, which comprises a step of melt molding the aromatic polyester polybutylene terephthalate resin composition obtained by the production method described in [3].

[5] The present invention further relates to a method for producing a film, which comprises a step of blending the master batch described in [1] with an aromatic polyester polybutylene terephthalate resin (c) and melt-kneading the blend, and a step of melt-molding the blend.

According to the present invention, it is possible to provide a film made of an aromatic polyester resin composition containing at least a PBT resin, which suppresses the occurrence of film defects, suppresses filter pressure rise when forming a film from the resin composition, and further suppresses the progression of resin deterioration, enabling stable film formation, as well as a method for producing the aromatic polyester resin composition and a film, and a masterbatch and a method for producing the same that can provide such an aromatic polyester resin composition for film.

The following describes an embodiment of the present invention. The present invention is not limited to the following embodiment.

<Master batch>
The master batch of the present embodiment is characterized in that it contains less than 15 parts by mass of fine particles (b) having an average particle size of 0.5 to 10 μm per 100 parts by mass of polybutylene terephthalate resin (a) having an intrinsic viscosity of 0.5 or more and less than 0.9.
The method for producing a masterbatch of the present embodiment is characterized by comprising a step of blending and melt-kneading 100 parts by mass of polybutylene terephthalate resin (a) having an intrinsic viscosity of 0.5 or more and less than 0.9 with less than 15 parts by mass of fine particles (b) having an average particle size of 0.5 to 10 μm.

[PBT resin (a)]
The PBT resin (a) used in the present invention has an intrinsic viscosity of 0.5 or more, preferably 0.6 or more, and less than 0.9, preferably 0.8 or less, because particle aggregation that causes film defects can be eliminated and resin deterioration that causes deterioration of film formability during film production can be suppressed.

The PBT resin used in the present invention has a structure in which terephthalic acid units and 1,4-butanediol (hereinafter sometimes abbreviated as BG) units are ester-bonded, and is a polymer in which 50 mol % or more of the dicarboxylic acid units are terephthalic acid units and 50 mol % or more of the diol component are BG units.

Here, the proportion of terephthalic acid units in all dicarboxylic acid units is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 95 mol% or more, and the proportion of BG units in all diol units is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 95 mol% or more.

In the present invention, the dicarboxylic acid component other than terephthalic acid is not particularly limited, and examples thereof include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid, alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid, and aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. These dicarboxylic acid components can be introduced into the polymer skeleton as dicarboxylic acids or using dicarboxylic acid derivatives such as dicarboxylic acid esters and dicarboxylic acid halides as raw materials.

In the present invention, there are no particular limitations on the diol components other than BG, and examples thereof include aliphatic diols such as ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, polypropylene glycol, polytetramethylene glycol, dibutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, and 1,8-octanediol; alicyclic diols such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,1-cyclohexanedimethylol, and 1,4-cyclohexanedimethylol; and aromatic diols such as xylylene glycol, 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, and bis(4-hydroxyphenyl)sulfone.

[Fine particles (b)]
The fine particles (b) used in the present invention have an average particle size of 0.5 μm or more, preferably 1.0 μm or more from the viewpoint of slipperiness, and 10 μm or less, and 8.0 μm or less from the viewpoint of transparency.
The fine particles used in the present invention are not particularly limited, but include, for example, wollastonite, sericite, kaolin, mica, clay, bentonite, asbestos, talc, silicate such as alumina silicate, metal oxide such as alumina, silicon chloride, magnesium oxide, zirconium oxide, titanium oxide, carbonate such as calcium carbonate, magnesium carbonate, dolomite, sulfate such as calcium sulfate, barium sulfate, glass beads, boron nitride, silicon carbide, silica, and other inorganic fine particles, which may be hollow. One or more of these may be used in combination. Among these, silica and alumina silicate are preferred from the viewpoint of imparting slipperiness to the film and being more transparent.

The microparticles used in the present invention may have a hydrophobic or hydrophilic surface, but it is more preferable that the surface is hydrophilic, since this will result in a more excellent transparency of the final film. The hydrophobic or hydrophilic surface of the microparticles used in the present invention can be made hydrophobic or hydrophilic by subjecting the surface to a known hydrophobic or hydrophilic treatment as necessary, and if the microparticles themselves have the desired hydrophobic or hydrophilic properties, they can be used without treatment.

The degree of hydrophobicity or hydrophilicity of the surface of the microparticles used in the present invention can be expressed, for example, by the DBA adsorption amount. In the case of hydrophobicity, the DBA adsorption amount is preferably in the range of less than 300 meq/kg, while in the case of hydrophilicity, the DBA adsorption amount is preferably in the range of 400 meq/kg or more. However, the DBA adsorption amount can be measured by the method in the Examples.

Examples of fine particles that can be suitably used in the present invention include the "SYLOPHOBIC" series of silica (silicon dioxide) fine particles manufactured by Fuji Silysia Chemical Co., Ltd., which are fine particles having a hydrophobic surface, while the "SYLYSIA" series of silicon dioxide fine particles manufactured by Fuji Silysia Chemical Co., Ltd., the "SEAHOSTAR" series of silica fine particles manufactured by Nippon Shokubai Co., Ltd., and the "SILTON" series of alumina silicate (aluminosilicate) fine particles manufactured by Mizusawa Industrial Chemical Co., Ltd., are fine particles having a hydrophilic surface.

The ratio of the PBT resin (a) and the fine particles (b) in the master batch is less than 15 parts by mass, preferably 10 parts by mass or less, of the fine particles (b) per 100 parts by mass of the PBT resin (a) in order to eliminate particle aggregation and prevent deterioration of film formability. There is no lower limit, but from the viewpoint of efficiency as a master batch, it is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more.

[Other ingredients]
The master batch may contain other components as optional components in addition to the essential components of the PBT resin (a) and the fine particles (b) within the scope of the gist of its function. Specific examples of other components include antioxidants, ultraviolet absorbers, colorants, pigments, dyes, foaming agents, lubricants, flame retardants, and fillers. When other components are used as optional components, their blending ratio is not particularly limited as long as it does not impair the effects of the present invention, but it is preferable to use them in a range of 50 parts by mass or less, and more preferably 25 parts by mass or less, relative to 100 parts by mass of the PBT resin (a). By adjusting the types and amounts of these components, the desired functions can be freely adjusted.

<Masterbatch manufacturing method>
The method for producing a masterbatch of the present invention includes a step of blending and melt-kneading the PBT resin (a) and the fine particles (b) (hereinafter, sometimes referred to as "step (1)").

First, the essential components of the PBT resin (a) and the fine particles (b) and, if necessary, the other components as optional raw material components are mixed in various forms such as bulk, pellets, chips, etc., to a predetermined mixing ratio, and then, after premixing as necessary, the mixture is put into a melt kneader and heated to the melting point of the PBT resin (a) or higher to melt-knead. The form of the melt-kneaded product is not particularly limited as long as it does not impair the effects of the present invention. It is also possible to directly add a diluent resin described below while the mixture is in the molten state to form the thermoplastic resin composition or molded product of the present invention, but it is preferable to extrude the mixture into a strand shape and then cut it into granular shapes such as pellets and chips.

In the step (1), the premixing is not particularly limited as long as it does not impair the effects of the present invention, and examples of the premixing include dry blending using a ribbon blender, a Henschel mixer, a V-blender, etc. Furthermore, the melt kneading machine is not particularly limited as long as it does not impair the effects of the present invention, and examples of the melt kneading machine include a Banbury mixer, a mixing roll, a single-screw or twin-screw extruder, and a melt kneading machine equipped with a heating mechanism such as a kneader. The melt kneading machine in the above step may be equipped with a filter having an opening of preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less.

The intrinsic viscosity of the masterbatch of the present invention thus obtained is not particularly limited, but is preferably 0.6 or more and preferably 0.9 or less.

<Aromatic polyester resin composition and molded article (film) thereof>
The method for producing the aromatic polyester resin composition and the molded article (film) of the present invention includes a step of blending and melt-kneading the master batch and the aromatic polyester resin (c) as a dilution resin (hereinafter, sometimes referred to as "step (2)"). The aromatic polyester resin composition or the molded article is a cured product (a product that is softened and flowed by heating and solidified by cooling) of the blend of the master batch and the aromatic polyester resin (c). The aromatic polyester resin composition is not particularly limited, but it is, for example, an intermediate molded article when obtaining a film from the master batch, and means a material having a predetermined form such as pellets or powder.

[Aromatic polyester resin (c)]
The aromatic polyester resin (c) used in the present invention is used as a diluting resin for the master batch. The aromatic polyester resin (c) used in the present invention is not particularly limited, but examples thereof include polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate (PBT), polyhexylene terephthalate, polycyclohexylene dimethylene terephthalate (PCT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polycyclohexane dimethyl phthalate (PCN), polytrimethylene naphthalate (PTN), amorphous polyester resin (PETG, PCTG), polyethylene-1,2-bis(phenoxy)ethane-4,4'-dicarboxylate, polyethylene isophthalate/terephthalate, polybutylene terephthalate/isophthalate, and the like. In addition, one type selected from these polyester resins may be used alone, or two or more types may be used in combination.

Of these, the aromatic polyester resin (c) may be the same as the PBT resin (a) listed above. When the PBT resin (c) is the same as the PBT resin (a) listed above, it may be the same type as the PBT resin (a) contained in the master batch or a different type, but from the viewpoint of compatibility, it is preferable to use the same type of resin.

The blending ratio of the master batch to the aromatic polyester resin (c) may be appropriately adjusted so that the content of the fine particles (b) is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and is preferably 3 mass% or less, more preferably 1.5 mass% or less, and even more preferably 1 mass% or less, when the total mass of the master batch and the aromatic polyester resin (c) in the aromatic polyester resin composition or film is taken as 100 mass%.
[Other ingredients]
The aromatic polyester resin composition or film may contain other components as optional components in addition to the essential components of the master batch and aromatic polyester resin (c) within the scope of the essential function.
Specific examples of other components include antioxidants, ultraviolet absorbers, colorants, pigments, dyes, foaming agents, lubricants, flame retardants, and fillers.

<Method of producing aromatic polyester resin composition and film>
In the method for producing an aromatic polyester resin composition or film according to the present embodiment, the essential components of the masterbatch and aromatic polyester resin (c) obtained by the above-mentioned production method, and other optional components as necessary, are mixed in various forms such as bulk, pellets, and chips to a predetermined mixing ratio, and then premixed as necessary, and then put into a melt kneader and heated to the higher melting point of the PBT resin (a) or the aromatic polyester resin (c) or higher to melt knead. This allows the film to be directly melt-molded to obtain the film, but it is also possible to obtain the desired film by first going through a process of obtaining a pellet-shaped or powdered aromatic polyester resin composition and then melt-molding the obtained pellet-shaped or powdered aromatic polyester resin composition. By obtaining a film via the masterbatch in this way, the fine particles can be more stably and uniformly dispersed in the film, and the desired functions and properties of the fine particles can be sufficiently imparted to the film. In addition, by molding a film via the masterbatch, hydrolysis of the aromatic polyester resin is significantly suppressed, and moldability (processability), mechanical properties, and appearance quality can be improved.

When the thermoplastic resin composition of the present invention is made into a film, the molten resin can be extruded (squeezed) through a slit-shaped hole after melt kneading to form a film or sheet. The film or sheet-shaped thermoplastic resin molded product (film) may be further molded by a press molding method or a vacuum molding method, or may be formed on a base layer to form a multilayer film.
In the present invention, the term "film" refers to a film- or sheet-shaped thermoplastic resin molded product, and is a general term that does not strictly distinguish between plate-shaped products such as films and sheets. In the present invention, the thickness of the film varies depending on its application and can be any thickness, but is usually preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, particularly preferably 0.3 μm or more, and most preferably 0.5 μm or more, and is preferably 1 mm or less, more preferably 500 μm or less, even more preferably 150 μm or less, particularly preferably 100 μm or less, and most preferably 70 μm or less.

Below, examples of the present invention are described. The present invention is not limited to the examples shown below. In the examples, unless otherwise specified, "parts" indicates mass %, and the units of values in the tables are parts by mass.

(Measurement Examples) Intrinsic Viscosity The intrinsic viscosity of a PBT resin was measured at a temperature of 23° C. by dissolving the PBT resin in an octochlorophenol solution.

(Measurement Example) DBA adsorption amount: 250 mg of dried sample was weighed out, 50 ml of N/500-di-n-butylamine solution (petroleum benzine solvent) was added, and the sample was left to stand at 20°C for approximately 2 hours. 5 ml of chloroform and 2-3 drops of indicator (crystal violet) were added to 25 ml of the supernatant, and the sample was titrated with N/100-perchloric acid solution (acetic anhydride solvent) until the purple color changed to blue, and the titration value at this point was recorded as A ml. A separate blank was run to record this as B ml, and the DBA adsorption amount was calculated using the following formula.

(where f is the titer of N/100-perchloric acid solution)

(Measurement example) Resin deterioration (intrinsic viscosity retention rate)
The retention rate of intrinsic viscosity was calculated to evaluate the state of resin deterioration. The closer the retention rate is to 100%, the better the resin deterioration is suppressed.

(Measurement Example) Filtration Pressure Increase of Masterbatch (MB) The differential pressure (filtration pressure increase) was measured when 1 kg of the masterbatch was passed through a single-screw extruder equipped with a filter having an aperture of 20 μm, and the particle aggregation was evaluated according to the following criteria. Note that a larger differential pressure indicates a larger amount of aggregated particles.
◎: Less than 0.5 MPa 〇: 0.5 MPa or more but less than 2 MPa △: 2 MPa or more but less than 5 MPa ×: 5 MPa or more

(Measurement Example) Agglomerated Particles in Film The prepared film was observed under an optical microscope, and the amount of agglomerated particles of 15 μm or more present per 100 cm ² was evaluated according to the following criteria.
◎: Less than 5 pieces 〇: Between 5 and 10 pieces △: Between 10 and 20 pieces ×: 20 pieces or more

(Measurement Example) Film Formability The stability during film formation was evaluated according to the following criteria.
◯: The state of the discharged material was stable, and film production was completed without any problems. △: Some decrease in viscosity of the discharged material, pulsation, fluctuation in discharge width, and foaming were observed, but film production was completed. ×: A stable film could not be obtained due to decrease in viscosity of the discharged material, pulsation, fluctuation in discharge width, and foaming.

Examples 1 to 6, Comparative Examples 1 to 2 (Production of Masterbatches)
PBT resin and fine particles were mixed in the mixing ratio shown in Table 1, dry blended, and then melt-kneaded in a 30 mmφ twin-screw extruder (set temperature 260°C). The resulting composition was pelletized to obtain a master batch.

The values in the table are based on mass, and the following components were used.
PBT-1: Polyplastics PBT resin "DURANEX 200FP" (intrinsic viscosity 0.6 dl/g)
PBT-2: Polyplastics PBT resin "DURANEX 500FP" (intrinsic viscosity 0.8 dl/g)
PBT-c1: Polyplastics PBT resin "DURANEX 600FP" (intrinsic viscosity 1.0 dl/g)
FP-1: Silica fine particles ("SYLYSIA (registered trademark) 550" manufactured by Fuji Silysia Chemical Ltd., average particle size 3.9 μm, DBA adsorption amount 800 meq/kg)
FP-2 Aluminosilicate fine particles ("SILTON (registered trademark) JC-50" manufactured by Mizusawa Industrial Chemicals, Ltd., average particle size 4.9 μm)
FP-3: Silica fine particles (manufactured by Fuji Silysia Chemical Ltd., "SYLOPHOBIC (registered trademark) 505", average particle size 3.9 μm, DBA adsorption amount 175 meq/kg)

Examples 7 to 12 and Comparative Examples 3 to 4 (Film Production)
A predetermined amount of PBT resin (DURANEX 300FP, intrinsic viscosity 0.7, manufactured by Polyplastics Co., Ltd.) and master batches (MB (1)-(4), MB (c1)-(c2)) were mixed so that the fine particle concentration in the film was 0.3 wt%, and dried at 120°C for 12 hours. Next, using an extruder connected to a 100 mm wide T-die, a film was formed at a film formation temperature of 260°C, and a film with a thickness of 30 μm was obtained. The obtained film was subjected to various measurements and the results are shown in Tables 3 and 4.

It was found that the films of Examples 7 to 12 obtained via the masterbatches produced in Examples 1 to 6 eliminated particle aggregation, which is a film defect, and suppressed resin degradation that causes deterioration of film formability during film production, due to the optimal intrinsic viscosity of the PBT resin used in the preparation of the masterbatches.
On the other hand, the films of Comparative Examples 3 and 4 obtained via the masterbatches produced in Comparative Examples 1 and 2 could not eliminate particle aggregation in the masterbatches, causing film defects and an increase in filter pressure during film production. It was also revealed that film production was impaired during film production due to the progression of resin deterioration.

Claims (8)

A method for producing a masterbatch, comprising the steps of blending and melt-kneading 100 parts by mass of polybutylene terephthalate resin (a) having an intrinsic viscosity of 0.5 or more and less than 0.9 with less than 15 parts by mass of fine particles (b) having a hydrophilic surface, an average particle size of 0.5 to 10 μm, and a DBA adsorption amount of 400 meq/kg or more. The method for producing a masterbatch according to claim 1 , characterized in that the fine particles (b) are silica. A method for producing an aromatic polyester resin composition exclusively used for films, comprising the steps of:
A method for producing an aromatic polyester resin composition, comprising the step of blending an aromatic polyester (c) with the masterbatch obtained by the method according to claim 1, and melt-kneading the blend. A method for producing a film, comprising a step of melt-molding the aromatic polyester resin composition obtained by the method according to claim 3 . A method for producing a film comprising the steps of blending and melt-kneading an aromatic polyester resin (c) with the master batch obtained by the method of claim 1, and melt-molding the blend. The method for producing a masterbatch according to claim 1, characterized in that after the melt-kneading step, the mixture is granulated. 4. The method for producing an aromatic polyester resin composition according to claim 3, wherein the content of the fine particles (b) is 0.01 mass% or more and 3 mass% or less when the total mass of the master batch and the aromatic polyester resin (c) is 100 mass%. The method for producing a masterbatch according to claim 1, characterized in that terephthalic acid units account for 95 mol% or more of all dicarboxylic acid units in the polybutylene terephthalate resin (a).