JP6872868B2 - Polyvinyl acetal resin and fiber with reduced odor - Google Patents

Description

The present invention relates to polyvinyl acetal resins and fibers with reduced odor.

Polyvinyl acetal can be obtained by acetalizing reaction in water under acidic conditions using polyvinyl alcohol (hereinafter, may be abbreviated as PVA) and an aldehyde compound. Since the film made of polyvinyl acetal is tough and has a unique structure having both a hydrophilic hydroxy group and a hydrophobic acetal group, it is used for various purposes, and various polyvinyl acetals have been proposed. There is. Among them, polyvinyl butyral (hereinafter, may be abbreviated as PVB) produced from PVA and butyraldehyde is excellent in adhesiveness and compatibility with various materials and solubility in organic solvents, and is a binder for ceramics. Widely used as an interlayer film for adhesives, inks, paints, and laminated glass. In recent years, it has also been proposed to use it as a fiber. For example, Patent Document 1 describes a non-woven fabric made of PVB, and by using it as an adhesive layer, a multilayer structure having excellent mechanical properties and sound absorbing properties. Is said to be obtained. However, polyvinyl acetal resins such as PVB have a problem that an odor is generated when they are handled, and in the case of a fiber molded product containing a polyvinyl acetal resin, the surface area is increased by forming the fiber shape. , The problem of odor generation becomes bigger. In addition, PVB produces a peculiar odor among polyvinyl acetals, and when it is molded into PVB fiber, the odor becomes particularly strong, and some workers who handle this may cause problems such as headaches due to the odor. was there.

A method for suppressing the generation of odor of polyvinyl acetal fiber has been studied. For example, in Patent Document 2, the odor of PVB fiber can be reduced by setting the degree of butyralization of PVB fiber and the content of butyraldehyde to specific values. It is stated that it is suppressed.

WO2006 / 101175 WO2014 / 157080

Although a method for suppressing the odor of the PVB resin to some extent has been studied as in the prior document 2, the effect of suppressing the odor is not yet sufficient, and further suppression of the odor is desired.
The present invention has been made to solve the above problems, and an object of the present invention is to provide a molded product such as a polyvinyl acetal resin in which a peculiar odor is suppressed and a fiber made of the polyvinyl acetal resin.

As a result of diligent studies, the present inventors have found that the odor generation mechanism of polyvinyl acetal is caused by a low molecular weight compound generated by the desorption of the side chain site of the polyvinyl acetal polymer. We have found that a phenol-based antioxidant or a hindered amine-based antioxidant having a specific molecular structure is effective as a means for suppressing desorption, and have completed the present invention.

That is, the present invention is a polyvinyl acetal resin containing a phenol-based antioxidant and / or a hindered amine-based antioxidant, and the antioxidant is an antioxidant having no phosphorus atom in its molecular structure. There, and phosphorus atom concentration of the polyvinyl acetal resin Ri der less 5 ppm, water content Ru der less 2000 ppm, a polyvinyl acetal resin.

Further, the polyvinyl acetal resin of the present invention may have an acid value of 0.03 mgKOH / g or less.

Further, in the present invention, the antioxidant may be an antioxidant having no sulfur atom in its molecular structure.

Further, the antioxidant may be an antioxidant composed of at least one atom selected from the group consisting only of carbon atoms, nitrogen atoms, oxygen atoms and hydrogen atoms.

Further, in the present invention, the polyvinyl acetal resin may be a polyvinyl butyral resin.

Further, the present invention may be a molded product made of the polyvinyl acetal resin.

Further, the present invention may be a fiber made of the polyvinyl butyral resin.

The present inventors consider that the cause of the generation of the odor of polyvinyl acetal is that the side chain of the polyvinyl acetal is cleaved and the low molecular weight compound is eliminated, and this low molecular weight compound is the cause of the odor. Various antioxidants that are particularly effective for suppression have been investigated.

The antioxidant added to the polymer compound is generally used for the purpose of preventing a decrease in the degree of polymerization due to the cleavage of the polymer main chain of the polymer compound, that is, a reduction in the molecular weight. As a mechanism for suppressing the reduction in molecular weight of antioxidants, for example, phenol-based antioxidants or hindered amine-based antioxidants have a radical collecting function, and phosphorus-based antioxidants have a peroxide decomposition function. The mechanisms that suppress the cleavage of the polymer main chain of each polymer compound are known. Antioxidants with different mechanisms are often used in combination, and have both a phenol moiety and a phosphorus moiety in the molecular structure of the antioxidant, and have both a radical collecting function and a peroxide decomposition function. Agents are also being developed.

The present inventors added an antioxidant having both a phenol moiety and a phosphorus moiety in the molecular structure to the polyvinyl acetal resin, which is said to be effective in suppressing the cleavage of the polymer main chain, but the odor suppressing effect was ineffective. It has been found that a phenolic antioxidant and / or a hindered amine-based antioxidant which is sufficient and does not have a phosphorus atom in the molecular structure has a higher odor suppressing effect.

From the above facts, the present inventors have an effective radical collecting function and a peroxide decomposition function of the phosphorus-based antioxidant from the viewpoint of preventing the elimination of the side chain instead of the polymer main chain. Rather, it is thought that it inhibits the desorption inhibitory effect of the side chain, and a phenolic antioxidant and / or a hindered amine antioxidant that does not have a phosphorus atom in the molecular structure is added to the polyvinyl acetal, and the polyvinyl acetal resin The present invention has been completed by finding that the elimination of polymer side chains can be effectively suppressed and the generation of odor can be reduced by setting the concentration of phosphorus atoms in the polymer to 5 ppm or less.

According to the present invention, it is possible to provide a polyvinyl acetal resin in which a specific odor is suppressed. Further, by molding the polyvinyl acetal resin, it is possible to provide a polyvinyl acetal molded product in which odor is suppressed. Further, by spinning the polyvinyl acetal resin, it is possible to provide a polyvinyl acetal fiber having suppressed odor.

The polyvinyl acetal resin used in the present invention is a resin obtained by acetalizing a polyvinyl alcohol-based resin with aldehydes.

Here, as the aldehydes used as raw materials, for example, formaldehyde, acetaldehyde, propionaldehyde, butylaldehyde, hexylaldehyde, benzaldehyde and the like are used, preferably an aldehyde compound having 1 to 12 carbon atoms, and more preferably carbon. It is a saturated alkylaldehyde compound having the number 1 to 6, and a saturated alkylaldehyde compound having 1 to 4 carbon atoms is particularly preferable. Of these, butyraldehyde is particularly preferable in terms of mechanical strength. Further, a single aldehyde may be used, or two or more kinds of aldehydes may be used in combination. Further, polyfunctional aldehydes and aldehydes having other functional groups may be used in combination in a small amount in a range of 20% by mass or less of all aldehydes.

The polyvinyl alcohol-based resin used as a raw material for the polyvinyl acetal resin is not particularly limited, and examples thereof include those obtained by polymerizing a vinyl ester-based monomer and saponifying the obtained polymer. Can be done. As a method for polymerizing the vinyl ester-based monomer, conventionally known methods such as a solution polymerization method, a massive polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied. As the polymerization initiator, an azo-based initiator, a peroxide-based initiator, a redox-based initiator, or the like is appropriately selected depending on the polymerization method. Alcohol decomposition, hydrolysis, etc. using a conventionally known alkali catalyst or acid catalyst can be applied to the saponification reaction, and among these, the saponification reaction using methanol as a solvent and a caustic soda (NaOH) catalyst is convenient. The degree of saponification of the polyvinyl alcohol-based resin which is the subject of the present invention is not particularly limited, but is preferably 95 mol% or more, and more preferably 98% or more.

Examples of the vinyl ester-based monomer used as a raw material for the polyvinyl alcohol-based resin include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatic acid, vinyl caproate, and caprylic acid. Examples thereof include vinyl, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl oleate, vinyl benzoate and the like, but vinyl acetate is particularly preferable.

Hereinafter, the present invention will be described using PVB, which is a uniform form of polyvinyl acetal, but the polyvinyl acetal of the present invention is not limited to PVB.

The PVB of the present invention is represented by the following chemical formula (I).

The degree of butyralization of PVB is represented by the content ratio of the repeating unit X in the polymer composition represented by the above chemical formula (I). The degree of butyralization is preferably 50 to 90% by mass, more preferably 55 to 85% by mass, from the viewpoint of resin fluidity.

The method for producing the PVB resin used in the present invention is not particularly limited, and a known method can be adopted. For example, polyvinyl alcohol can be obtained by saponifying a polyvinyl ester obtained by polymerizing a vinyl ester monomer, and a PVB resin can be obtained by butyralizing the polyvinyl alcohol.

Polyvinyl alcohol can be obtained, for example, by saponifying a polyvinyl ester obtained by polymerizing a vinyl ester monomer. As a method for polymerizing the vinyl ester monomer, a known method such as a solution polymerization method, a massive polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied. At that time, as the polymerization initiator, an azo-based initiator, a peroxide-based initiator, a redox-based initiator, or the like may be appropriately selected according to the polymerization method.

Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatic acid, vinyl caproate, vinyl caprylate, vinyl laurate, and vinyl palmitate. , Vinyl stearate, vinyl oleate, vinyl benzoate and the like may be used, and vinyl acetate is particularly preferable. When polymerizing the vinyl ester monomer, other monomers may be copolymerized as long as the gist of the present invention is not impaired.

As the saponification method, known methods such as a method by alcohol decomposition using an alkali catalyst or an acid catalyst, a method by hydrolysis, and the like can be adopted. Among them, methanol is used as a solvent and caustic soda is used as a catalyst. The method using (NaOH) is preferable because it is simple. The polyvinyl alcohol obtained by saponifying the polyvinyl ester obtained by polymerizing the vinyl ester monomer contains a vinyl alcohol unit and a vinyl ester unit. For example, when vinyl acetate is used as the vinyl ester monomer, the polyvinyl alcohol obtained by the above production method contains a vinyl alcohol unit and a vinyl acetate unit.

Butyralization of polyvinyl alcohol may be carried out based on a known method. For example, polyvinyl alcohol and n-butyraldehyde (hereinafter, may be simply referred to as butyraldehyde) may be mixed in the presence of an acid catalyst. .. The acid catalyst is not particularly limited, and either an organic acid or an inorganic acid may be used, and for example, acetic acid, p-toluenesulfonic acid, nitric acid, sulfuric acid, hydrochloric acid and the like may be used. Of these, a method using hydrochloric acid, sulfuric acid, or nitric acid is common, and it is particularly preferable to use hydrochloric acid.

As a specific method for producing the PVB resin, the following method is exemplified as a typical method. First, an aqueous solution of polyvinyl alcohol at 80 to 100 ° C. (concentration: 3 to 15% by mass) is prepared, and the temperature of the aqueous solution is gradually lowered to −10 to 30 ° C. over 10 to 60 minutes. Then, butyraldehyde and an acid catalyst are added to the aqueous solution to allow the butyralization reaction to proceed for 30 to 300 minutes while maintaining the temperature at −10 to 30 ° C., and then the temperature rises to 30 to 80 ° C. over another 30 to 200 minutes. Allow to warm and hold in this temperature range for 1-8 hours. The polyvinyl butyral powder can be obtained by subsequently performing neutralization treatment with alkali, washing with water, and then drying.

In the present invention, it is important to add a phenolic antioxidant and / or a hindered amine-based antioxidant having no phosphorus atom in the molecular structure to the PVB resin, and such an antioxidant is added. By doing so, the odor of PVB can be reduced.

The mechanism by which phenolic antioxidants and / or hindered amine antioxidants that do not have a phosphorus atom in their molecular structure work effectively to reduce odors is unclear, but they do not have a phosphorus atom in their molecular structure. In phenol-based antioxidants and / or hindered amine-based antioxidants, the radical collection mechanism mainly works as a mechanism for suppressing polymer chain cleavage, and this radical collection function causes the generation of odor in PVB, which is a polymer side chain. That is, it is presumed that it remarkably works to suppress the detachment of the side chain of the repeating unit X as represented by the chemical formula (I) and contributes to the prevention of the generation of butanoic acid, which is the cause of odor.

Further, from the viewpoint of not inhibiting the odor suppression mechanism, the phenol-based antioxidant and / or the hindered amine-based antioxidant may be an antioxidant having no sulfur atom in its molecular structure, particularly. The antioxidant may be an antioxidant composed of at least one atom selected from the group consisting only of carbon atoms, nitrogen atoms, oxygen atoms and hydrogen atoms.

Examples of the phenolic antioxidant include 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate, 2, 4-dit-amyl-6. -(1- (3,5-dit-amyl-2-hydroxyphenyl) ethyl) acrylate-based compounds such as phenylacrylate; 2,6-dit-butyl-4-methylphenol, 2,6-dit- Butyl-4-ethylphenol, octadecyl-3- (3,5-dit-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis (4-methyl-6-t-butylphenol), 4, 4'-butylidene-bis (4-methyl-6-t-butylphenol) 4, 4'-butylidene-bis (6-t-butyl-m-cresol) 4, 4, 4'-thiobis (3-methyl-6) − T − Butylphenol), bis (3-cyclohexyl-2-hydroxy-5-methylphenyl) methane, 3, 9 − bis (2- (3- (3-t − butyl − 4 − hydroxy-5 − methylphenyl)) Propionyloxy) -1, 1-dimethylethyl) -2, 4, 8, 1, 10-tetraoxaspiro [5. 5] Undecane, 1, 1, 3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1, 3, 5-trimethyl-2, 4, 6-tris (3, 5-di) t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3', 5'-di t-butyl-4'-hydroxyphenyl) propionate) methane, triethylene glycolbis (3- (3-t) -Alkyl-substituted phenolic compounds such as − butyl-4-hydroxy-5-methylphenyl) propionate); 6 − (4-hydroxy-3, 5-di t − butylanilino) −2, 4-bis-octylthio-1, 3 , 5-Triazine, 6- (4-Hydroxy-3,5-Dimethylanilino) -2, 4-Bis-octylthio-1, 3, 5-Triazine, 6- (4-Hydroxy-3-methyl-5- t-butylanilino) -2, 4-bis-octylthio-1, 3, 3, 5-triazine, 2-octylthio-4, 6-bis- (3, 5-di t-butyl-4--4-oxyanilino) -1, 3, 5-There are triazine group-containing phenolic compounds such as triazine.
Specifically, SUMILIZER BBM-S (manufactured by Sumika Chemtex), IRGANOX 245FF (manufactured by BASF) and the like are commercially available.

As hindered amine antioxidants, bis (2, 2, 6, 6-tetramethyl-4-piperidyl) sebacate, bis (1, 2, 2, 6, 6, 6-pentamethyl-4-piperidyl) sebacate, 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, 8-benzyl-7, 7, 9, 9, 9-Tetramethyl-3-octyl-1, 1, 3, 8-triazaspiro [4, 5] Undecane-2, 4 − Dione, 4-benzoyloxy-2, 2, 6, 6-tetramethylpiperidine, dimethyl succinate-1- (2-hydroxyethyl) -4-hydroxy-2, 2, 6, 6-tetramethylpiperidine polycondensation Thing, poly [[6- (1, 1, 3, 3-tetramethylbutyl) imino-1, 3, 5-triazine-2, 4-diimyl] [(2, 2, 6, 6-tetramethyl-4) -Piperidyl) imino] hexamethylene [(2, 3, 6, 6-tetramethyl-4-piperidyl) imino]], 2- (3, 5-di-t-butyl-4-hydroxybenzyl) -2 − n − Butyl malate bis (1, 2, 2, 6, 6 − pentamethyl-4-piperidyl), N, N ′ − bis (3-aminopropyl) ethylenediamine − 2, 4- bis [N − butyl − N− ( 1, 2, 2, 6, 6,-pentamethyl-4 piperidyl) amino] -6-chloro-1, 1, 3, 5-triazine condensate and the like.
Specifically, TINUVIN 770DF (manufactured by BASF), TINUVIN 765 (manufactured by BASF), TINUVIN 123 (manufactured by BASF) and the like are commercially available.

These antioxidants can be used alone or in combination of two or more. The amount of the antioxidant to be blended is not particularly limited, but is preferably 100 ppm to 10000 ppm, more preferably 500 to 5000 ppm, based on the mass of the resin, from the viewpoint of exhibiting the effect of the antioxidant and spinnability. is there.

Further, in the present invention, it is important that the phosphorus atom concentration in PVB is 5 ppm or less, more preferably 1 ppm or less, and further preferably substantially free of phosphorus atoms. By setting the phosphorus atom concentration to 5 ppm or less, the odor-reducing effect of the phenol-based antioxidant or hindered amine-based antioxidant added to PVB, which does not have a phosphorus atom in its molecular structure, can be remarkably exhibited. Can be done.

When phosphorus atoms are contained in the molecular structure of the antioxidant added to PVB, or when the phosphorus atom concentration in polyvinyl acetal exceeds 5 ppm, the odor suppressing effect cannot be sufficiently obtained. It is presumed that this is because the peroxide collecting function of the phosphorus atom contained in the antioxidant and PVB inhibits the radical collecting mechanism for suppressing the elimination of the polymer side chain.

Further, the PVB resin of the present invention preferably has an acid value of 0.03 mgKOH / g or less, and more preferably 0.02 mgKOH / g or less. When the acid value of the PVB resin is within the above range, the amount of butyric acid generated from PVB during melt spinning is small, and the odor is reduced.

In the step of adding the antioxidant of the present invention to PVB, the melt flow rate (hereinafter, abbreviated as MFR) at 150 ° C. and 2.16 kgf is 0.2 g / 10 min to 45 g / 10 min. PVB and the antioxidant may be melt-kneaded. By preparing the molten resin by this method, a predetermined concentration of the antioxidant can be uniformly dispersed, and a PVB resin in which the function of the antioxidant of the present invention is effectively exhibited can be produced. be able to.

In the above method of melt-kneading, it is preferable to put PVB and an antioxidant into an extruder, reduce the pressure using at least one vent, and melt-knead while degassing the odorous substance. As the extruder, a single-screw extruder or a twin-screw extruder can be used, and an extruder having a plurality of vents is preferable. The resin temperature during melt-kneading is preferably more than the melt temperature of PVB and 220 ° C. or lower. By melt-kneading at a relatively low temperature of 220 ° C. or lower, the amount of butyric acid generated from the obtained PVB can be reduced.

In the present invention, the step of adding the antioxidant to PVB is not particularly limited, but for example, the antioxidant of the present invention may be added at the time of melt-kneading for producing a PVB resin. Since PVB is decomposed by the heat during the production of the PVB resin and various odorous substances such as butanoic acid are generated, the antioxidant of the present invention is put into the extruder during the melt-kneading in the production process of the PVB resin. As a result, the decomposition of PVB during melt-kneading can be suppressed, and the odor can be suppressed.

The water content of PVB used in the production of the PVB resin is preferably 5% by mass or less. When the water content is 5% by mass or less, the degassing of butyric acid is not hindered by the degassing of excess water, so that the butyric acid content of the obtained PVB resin can be reduced. Further, from the viewpoint of suppressing the scattering of powdery PVB, the water content is preferably 0.1% by mass or more. Examples of the method of adjusting the water content of PVB within the above range include a method of adjusting the drying conditions after the neutralization treatment and washing with water.

After melt-kneading with an extruder as described above, the resin is extruded and then cut to obtain a PVB resin. As the extrusion method, a method of extruding the molten resin into a strand shape is preferable. As a cutting method, a method of cutting with a cutter such as a rotary cutter is preferable.

The PVB molded product of the present invention can be obtained by molding the PVB resin.

As a molding method for the PVB resin of the present invention, a known molding technique can be used. Specifically, any molding method such as an injection molding method, an extrusion molding method, a press molding method, a blow molding method, a calender molding method, or a casting molding method can be adopted. Further, general T-die method, calendar method, inflation method, belt method and the like can be adopted for forming films and sheets.

The PVB resin molded product of the present invention may be a fiber. Normally, in the fiber shape, the amount of odor-causing substances generated from the resin diffuses into the air becomes larger due to the larger surface area than the pellet-shaped resin having a size of several mm, so that the fiber shape is formed. The odor tends to be stronger by molding, but the resin of the present invention has a remarkable odor suppressing effect even when it has a fiber shape.

The PVB fiber of the present invention can be obtained by melt-spinning the PVB resin. In the resin drying step at the time of melt spinning, the PVB resin may be dried until the water content becomes 2000 ppm or less. The water content is preferably 1000 ppm or less, more preferably 500 ppm or less. When the water content of the PVB resin is within this range, the generation of butyric acid from PVB can be suppressed during melt spinning, and there is no problem in the fibrosis step.

In the step of melt-spinning the PVB resin of the present invention, it is preferable to melt-spin the PVB resin at a low temperature. As a result, the amount of butyric acid generated in the heat treatment in the spinning process can be suppressed. The spinning temperature is preferably 170 ° C. or higher and 250 ° C. or lower, and more preferably 170 ° C. or higher and 240 ° C. or lower. If the spinning temperature is less than 170 ° C., the resin viscosity becomes too high and it becomes difficult to fiberize the resin. If the temperature is 250 ° C. or higher, the amount of butyric acid generated from the PVB resin increases remarkably and the odor becomes severe.

The PVB fiber of the present invention may be a single fiber composed of only PVB, a composite fiber containing PVB as one of the components, or a mixed fiber containing PVB as one of the components, and PVB is one of the components. Any fiber contained in the above may be used. Here, examples of the composite fiber include a core-sheath type composite fiber using another polymer as a core component and PVB as a sheath component, and a split type composite fiber having a structure in which another polymer and PVB are bonded together. The PVB fiber of the present invention may be a long fiber or a short fiber.

In order to obtain the PVB fiber of the present invention, the MFR of the PVB resin is preferably 0.5 g / 10 minutes to 45 g / 10 minutes, more preferably 1 g / 10 minutes, from the viewpoint of spinnability and fiber strength. ~ 40 g / 10 minutes.

In the spinning process for producing the PVB fiber of the present invention, the molten PVB resin is spun from the mouthpiece using a normal molten spinning apparatus. The cross-sectional shape and diameter of the obtained fiber can be arbitrarily set depending on the shape and size of the base.

The melt-spun PVB fiber is once cooled to a temperature equal to or lower than the glass transition temperature of the PVB fiber, preferably to a temperature 10 ° C. or higher lower than the glass transition temperature. In this case, the cooling method and the cooling device are not particularly limited as long as they can cool the spun PVB fiber to the glass transition temperature of the PVB fiber or less, but the cooling of a cooling air blowing cylinder or the like under the spinneret is not particularly limited. It is preferable to provide a wind blowing device and blow the cooling air on the spun PVB fibers to cool the PVB fibers below the glass transition temperature. There are no particular restrictions on the cooling conditions such as the temperature and humidity of the cooling air, the blowing speed of the cooling air, and the blowing angle of the cooling air with respect to the spun yarn, and the PVB fibers spun from the base cause shaking of the fibers. It is preferable that the conditions are such that the PVB fiber can be cooled quickly and uniformly to the glass transition temperature or lower while preventing the cooling air from being cooled. High-quality cooling is performed by setting the wind blowing speed to 0.4 to 1.0 m / sec and cooling the spun PVB fibers with the cooling air blowing direction to the spun fibers perpendicular to the spun direction. It is more preferable because PVB fibers can be obtained smoothly. In addition, when cooling is performed under the above conditions using a cooling air blowing cylinder, a cooling air blowing cylinder having a length of about 80 to 120 cm is installed directly under the spinneret with a slight interval or no interval. It is preferable to arrange it.

After spinning, the yarn was once cooled to a temperature below the glass transition temperature of the PVB fiber, and then the yarn was directly run in a heating zone, specifically, in a device such as a tube-type heating cylinder, and stretch-heat-treated to apply an oil agent. Later, by winding at a speed of 2000 to 5000 m / min, a drawn yarn having good productivity and stable quality can be obtained. The winding speed of the PVB fiber is more preferably 2500 to 4000 m / min. When the winding speed of the PVB fiber is less than 2000 m / min, the productivity is lowered, the fiber is not sufficiently stretched in the heating zone, and the mechanical properties of the obtained PVB fiber are lowered. When the winding speed exceeds 5000 m / min, it is difficult to obtain stable high-speed spinnability, the fibers are not sufficiently stretched in the heating zone, and the mechanical properties of the obtained PVB fibers are lowered.

It is preferable to apply an oil agent to the fibers. The oil agent is applied after passing through the stretching treatment step by the heating device. This reduces stretched yarn breakage due to the oil agent. The oil agent application method may be either a gear pump method or an oiling nozzle application method or an oiling roller application method. However, as the spinning speed increases, the former method enables more stable application of oil to the yarn without spots. The amount of the oil agent attached is not particularly limited, and may be appropriately adjusted as long as it has an effect of suppressing yarn breakage and yarn fluff and is suitable for the manufacturing process of the fiber aggregate. The amount of the oil adhering to the PVB fiber is preferably 0.3 to 2.0% by mass because high quality PVB fiber can be smoothly obtained, and is preferably 0.3 to 1.0% by mass. Is more preferable.

Further, various additives may be added to the resin and the molded product of the present invention as long as the effects of the present invention are not impaired. For example, colorants such as pigments and dyes, heat stabilizers, light stabilizers, and ultraviolet rays may be added. Absorbents, weather resistance improvers, plasticizers, antistatic agents, flame retardants and the like may be added.

Since the fiber of the present invention has a low odor and the fabric produced from the fiber has excellent formability, the fabric produced from the fiber of the present invention has a low odor that cannot be realized by, for example, a film. It is possible to produce a molded product having a required complicated shape.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, each physical property value in an Example was measured by the following method.

[Phosphorus atom concentration of PVB resin]
The phosphorus atom concentration of the PVB resin was calculated from the amount of the antioxidant added to the PVB resin and the phosphorus atom concentration in the antioxidant.

[Acid value of PVB resin]
The quantification of the acid value of the PVB resin was measured based on the provisions of JIS K6728: 1977.

[Quantitative value of butyric acid in PVB resin]
The butyric acid quantitative value was calculated from the acid value of the PVB resin. Butyric acid contained in 1 g of PVB resin was calculated by the following formula using the acid value of PVB resin.

Amount of butyric acid contained in 1 g of PVB sample = acid value of PVB resin × (molar mass of butyric acid / molar mass of KOH)

However, the molar mass of butyric acid was 88.11 g / mol, and the molar mass of KOH was 56.11 g / mol.

[Moisture content of PVB resin]
The water content of the PVB resin was determined by measuring the amount of water generated at 170 ° C. in a nitrogen atmosphere using a trace water content measuring device (manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

[Melt Flow Rate (MFR)]
The MFR survey is measured according to the JIS K7210 test method and is indicated by the discharge rate for 10 minutes when the polymer melted at 150 ° C. is extruded from the capillary under a load of 2.16 kgf.

[Fiber odor sensory evaluation]
When spinning the PVB resin at a spinning temperature of 240 ° C., the odor at a place 2 m away from the spinning nozzle was confirmed by a sensory test and evaluated according to the following criteria.
A: Almost no odor was felt.
B: A little odor was felt.
C: An odor was felt.
D: A strong odor was felt.

[Example 1]
SUMILIZER BBM-S (manufactured by Sumika Chemtex, 4,4'-butylidenebis (6-tert-butyl-3-methylphenol)) is used as a PVB resin as a phenolic antioxidant that does not have a phosphorus atom in its molecular structure. On the other hand, PVB resin pellets prepared by adding so that the addition amount was 500 ppm and melting and kneading at 210 ° C. were used, and the spinning temperature was 240 ° C. and the single-hole discharge amount was 1.57 g, each using a mouthpiece with 24 holes. Melt spun at / min. Immediately after spinning, a cooling air having a temperature of 20 ° C. and a humidity of 60% is blown at a speed of 0.5 m / sec to reduce the temperature of the yarn to 50 ° C or less, and then at a position 1.2 m below the spinneret. After introducing it into a tube heater (internal temperature 130 ° C) with an installed length of 1.0 m, an inlet guide diameter of 8 mm, an outlet guide diameter of 10 mm, and an inner diameter of 30 mmΦ and stretching it in the tube heater, it is applied to the thread coming out of the tube heater. A hydrophobic spinning oil is lubricated to 1% by mass with respect to the fiber with an oiling nozzle, and wound at a speed of 3500 m / min via two take-up rollers. 84T / 24f PVB fiber (hereinafter, PVB filament). (Sometimes referred to as) was obtained. The odor sensory evaluation results are shown in Table 1.

[Example 2]
As a phenolic antioxidant that does not have a phosphorus atom in its molecular structure, IRGANOX 245 FF (manufactured by BASF, ethylene bis (oxyethylene) bis- (3- (5-tert-butyl-4-hydroxy-m-tolyl)) ) Propionate)) was used to obtain PVB filaments under the same conditions as in Example 1. The odor sensory evaluation results are shown in Table 1.

[Example 3]
TINUVIN 770 DF (BASF, 1,10-bis (2,2,6,6-tetramethyl-4-piperidinyl) ester of decanoic acid), which is a hindered amine-based antioxidant that does not have a phosphorus atom in its molecular structure. ) Was used, and filaments were obtained under the same conditions as in Example 1. The odor sensory evaluation results are shown in Table 1.

[Comparative Example 1]
As an antioxidant, IRGASTAB FS301 FF (BASF, N, N-dioctadecylhydroxyamine and tris phosphite (2,4-di-tert), which is a mixture of a phosphorus-based antioxidant and a hindered amine-based antioxidant. A filament was obtained under the same conditions as in Example 1 except that a mixture of −butylphenyl) was used. The odor sensory evaluation results are shown in Table 1.

[Comparative Example 2]
As an antioxidant, a phenol phosphorus-based antioxidant, SUMILIZER GP (manufactured by Sumitomo Chemical Co., Ltd., 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4 Filaments were obtained under the same conditions as in Example 1 except that 8,10-tetra-tert-butyldibenzo [d, f] [1,3,2] dioxaphosfepine) was used. The odor sensory evaluation results are shown in Table 1.

[Comparative Example 3]
Filaments were obtained under the same conditions as in Example 1 except that they were melt-kneaded at 240 ° C. without adding an antioxidant. The odor sensory evaluation results are shown in Table 1.

[Comparative Example 4]
Filaments were obtained under the same conditions as in Example 1 except that no antioxidant was added. The odor sensory evaluation results are shown in Table 1.

[Example 4]
A circular knitted fabric was prepared using the filament obtained in Example 1. A sensory test was conducted at a position 10 cm away from the circular knitted fabric, but almost no odor was felt.

From the above, in Examples 1 to 3 using a phenol-based antioxidant or a hindered amine-based antioxidant having no phosphorus atom in the molecular structure, the acid value and butyric acid quantitative value of the PVB resin were low, and the odor sensory evaluation was good. Met. On the other hand, in Comparative Example 1 in which an antioxidant containing both a phosphorus-based antioxidant and a hindered amine-based antioxidant was used, the phosphorus atom concentration of the PVB resin exceeded 5 ppm, and the odor reducing effect of the hindered amine-based antioxidant was obtained. However, the acid value of the PVB resin and the quantitative value of butanoic acid were high, and a little odor was felt in the odor sensory evaluation. Further, even in Comparative Example 2 in which a phenol phosphorus-based antioxidant having a phosphorus atom was added to the molecular structure, the odor reducing effect was insufficient, the acid value and butyric acid quantitative value of the PVB resin were high, and the odor was evaluated in the odor sensory evaluation. Was felt a little. Further, in Comparative Example 3 in which the melt kneading temperature was high without adding an antioxidant, the acid value and the butyric acid quantitative value of the PVB resin were very high, and a strong odor was felt even in the sensory test. In Comparative Example 4 in which the antioxidant was not added, the acid value and the butyric acid quantitative value of the PVB resin could be reduced, but an odor was felt in the functional group evaluation, and the odor suppressing effect was not sufficient.

The polyvinyl acetal resin of the present invention has a low odor property, and by suppressing the odor generated during resin molding, it is possible to improve the working environment and obtain various resin molded products in which the odor generated from the resin is suppressed. it can. In particular, the present invention is useful for fibers, and is expected to be applied to the apparel field, medical / hygiene field, etc., where the use of polyvinyl acetal resin has been scarce due to the problem of odor.

Claims (5)

A polyvinyl acetal resin containing a phenol-based antioxidant and / or a hindered amine-based antioxidant, the antioxidant being an antioxidant having no phosphorus atom in its molecular structure, and the polyvinyl acetal resin. A fiber containing a polyvinyl acetal resin having a phosphorus atom concentration of 5 ppm or less and a water content of 2000 ppm or less. The fiber according to claim 1, wherein the polyvinyl acetal resin has an acid value of 0.03 mgKOH / g or less. The fiber according to claim 1 or 2, wherein the antioxidant is an antioxidant having no sulfur atom in its molecular structure. According to any one of claims 1 to 3, the antioxidant is an antioxidant composed of at least one atom selected from the group consisting of only carbon atoms, nitrogen atoms, oxygen atoms and hydrogen atoms. Described fiber . The fiber according to any one of claims 1 to 4, wherein the polyvinyl acetal resin is a polyvinyl butyral resin.