TW201936658A - Resin material, production method therefor, and water-soluble film - Google Patents

Abstract

Provided is a resin material capable of giving a water-soluble film which has sufficient water solubility and, despite this, shows reduced solubility in the beginning of immersion in water. Also provided is a production method by which the resin material can be easily obtained. Furthermore provided is a water-soluble film which has sufficient water solubility and, despite this, shows reduced solubility in the beginning of immersion in water. The resin material comprises a modified vinyl-alcohol-based polymer (A) as the main component, wherein the modified vinyl-alcohol-based polymer (A) has, in a side chain, both a sulfonic acid group or salt thereof and an aromatic ring bonded to the sulfonic acid group or salt thereof and the amount in which the modified vinyl-alcohol-based polymer (A) has been modified with the sulfonic acid group or salt thereof is 0.01-10 mol%, the resin material having an inorganic-salt content of 100 ppm or less.

Description

   Resin material, manufacturing method thereof, and water-soluble film   

The present invention relates to a resin material containing a modified vinyl alcohol polymer having a sulfonic acid group or a salt thereof as a main component in a side chain, and a method for producing the same. The present invention relates to a water-soluble film formed from the resin material.

Compared with general-purpose PVA, vinyl alcohol-based polymers having a sulfonic acid group (hereinafter referred to as vinyl alcohol-based polymers are simply referred to as "PVA") have a higher rate of dissolution in water. it works. In recent years, various medicines including pesticides, washing detergents, bleaching agents, cosmetic products, industrial medicines, etc. have been sealed and packaged with water-soluble films to the same constant amount. The method of putting the packaging form into water and dissolving or dispersing the contents together with the packaging film in water. This type of packaging is called unit packaging and the like. The advantages of unit packaging are that it can be used without direct contact with dangerous drugs during use, and the content is packaged in a certain amount, so no measurement is required during use, and no need to dispose of the container after use.

As a method for producing a PVA having a sulfonic acid group, Patent Document 1 discloses a method of saponifying a copolymer of an acrylamide-based polymerizable monomer containing a sulfonic acid group and a vinyl ester. As another method for producing PVA having a sulfonic acid group, Patent Document 2 discloses a method of swelling PVA with water and performing an acetalization reaction using an aldehyde containing a sulfonic acid group in the presence of an acid catalyst. Patent Document 3 discloses a method of introducing a sulfonic acid group by mixing PVA with a sulfonic acid group-containing monomer, and then graft-polymerizing the sulfonic acid group-containing monomer to the PVA.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Unexamined Patent Publication No. 7-118407

[Patent Document 2] Japanese Patent Application Laid-Open No. 10-101729

[Patent Document 3] Japanese Patent Laid-Open No. 2006-291161

However, in the method of Patent Document 1, the acrylamide skeleton of the copolymer is hydrolyzed. As a result, there is a disadvantage that the introduction effect is reduced due to the release of the sulfonic acid group. Further, in the methods such as Patent Documents 2 and 3, since PVA is dissolved in water and reacted with the compound containing a sulfonic acid group, a drying step is required until a powder of the PVA into which the sulfonic acid group is introduced is obtained. Multi-stage steps.

In addition, in the above-mentioned applications such as unit packaging, from the viewpoint of operability, etc., a water-soluble film having a property of not dissolving immediately after being immersed in water and being dissolved in a single breath after being immersed in water is desired. . However, the PVA having a sulfonic acid group obtained by a conventional production method cannot obtain a thin film having such characteristics.

The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a resin material which can obtain a water-soluble film having sufficient water solubility while suppressing the solubility at the initial stage of immersion in water. Moreover, this invention aims at providing the manufacturing method which can obtain this resin material easily. Furthermore, the present invention aims to provide a water-soluble film that has sufficient water solubility while suppressing the solubility in the initial stage of immersion in water.

The present inventors diligently studied and found that in the thin film formed by the PVA having a sulfonic acid group obtained by the conventional manufacturing method, the residual inorganic salts such as the catalyst have an influence on the solubility in the initial stage of immersion in water, and have completed the present invention. invention.

That is, the present invention is a resin material which is a resin material having a modified vinyl alcohol polymer (A) as a main component, wherein the modified vinyl alcohol polymer (A) has a sulfonic acid group in a side chain or A salt, an aromatic ring bonded to the sulfonic acid group or a salt thereof, and a modification amount of the sulfonic acid group or the salt thereof in the modified vinyl alcohol polymer (A) is 0.01 mol% or more and 10 mol % Or less, and the content of the inorganic salt is 100 ppm or less.

In this case, it is preferable that the above-mentioned salt is an alkali metal salt.

At this time, it is preferable that the viscosity of a 4% by mass aqueous solution of the modified vinyl alcohol polymer (A) is 2 mPa · s or more and 20 mPa · s or less. In this case, the saponification degree of the modified vinyl alcohol polymer (A) is preferably 60 mol% to 99 mol%. In this case, it is also preferred that the block characteristics of the remaining vinyl ester units of the modified vinyl alcohol polymer (A) be 0.55 or more and 1 or less. It is also preferable that the resin material further contains a plasticizer.

In addition, the present invention is a method for producing a resin material, comprising: substantially not using an inorganic acid or a salt thereof as a catalyst; and mixing a 4% by mass aqueous solution under heating at a temperature of 80 ° C to 240 ° C to a viscosity of 20 mPa · s or less A step of a vinyl alcohol polymer (B) and an aldehyde having a sulfonic acid group or a salt thereof.

In this case, it is preferable that the vinyl alcohol polymer (B) and the aldehyde having a sulfonic acid group or a salt thereof are mixed in a molten state in the mixing step. In this case, it is preferable to perform mixing in the above-mentioned mixing step in the absence of a solvent substantially.

Furthermore, at this time, the block characteristics of the remaining vinyl ester units in the vinyl alcohol polymer (B) and the embedding of the remaining vinyl ester units in the modified vinyl alcohol polymer (A) are also used. The difference in segment characteristics is preferably 0.05 or more and 0.4 or less.

The water-soluble film formed by the resin material is also an ideal embodiment of the present invention.

The resin material of the present invention can obtain a water-soluble film that has sufficient water solubility and can suppress the solubility at the initial stage of immersion in water. Furthermore, according to the manufacturing method of the present invention, such a resin material can be easily obtained. Furthermore, the water-soluble film of the present invention has sufficient water solubility, and at the same time can suppress the solubility in the initial stage of immersion in water.

    <Resin material>    

The resin material of the present invention is characterized in that a modified vinyl alcohol polymer (A) (hereinafter referred to as "modified PVA (A)") is used as a main component, and the modified PVA (A) has a sulfonic acid group in a side chain or The salt and an aromatic ring bonded to the sulfonic acid group or a salt thereof, the modification amount of the sulfonic acid group or a salt thereof is 0.01 mol% or more and 10 mol% or less, and the content of the inorganic salt is 100 ppm or less.

Since the resin material of the present invention contains a modified PVA (A) having a modification amount of the sulfonic acid group or a salt thereof in the specific range as a main component, a water-soluble film having sufficient water solubility can be obtained. Moreover, since this resin material has an inorganic salt content of 100 ppm or less, a water-soluble film capable of suppressing the solubility in the initial stage of immersion in water can be obtained. The reason is not necessarily clear, but it is speculated that there are the following reasons. The sulfonic acid-modified vinyl alcohol-based polymer obtained by the conventional manufacturing method inevitably remains an inorganic salt used as a catalyst. Compared with the modified PVA (A), the inorganic salt has higher water solubility. Therefore, if such an inorganic salt is present in a large amount in a water-soluble film, the inorganic salt will dissolve shortly after being immersed in water, and the dissolved portion of the inorganic salt will easily permeate water, and the modified PVA (A) will be impregnated from Water is also easy to dissolve in the beginning. In contrast, it is speculated that the water-soluble film formed of the resin material of the present invention has a very small content of inorganic salts, and therefore, it becomes difficult for water to penetrate into the film at the initial stage of immersion in water. As a result, the initial stage of immersion can be suppressed. Solubility. In addition, if the water-soluble film formed of the resin material of the present invention is immersed in water for a while, water will start to penetrate into the film due to the deformation and local dissolution of the film. Once the water starts to penetrate into the inside, the modified PVA (A) becomes dissolved in one breath due to its high water solubility.

    (Modified PVA (A))    

The modified PVA (A) is a main component of the resin material of the present invention. The main component refers to the component with the highest content on a mass basis. The lower limit of the content of the modified PVA (A) in the resin material is preferably 50% by mass, 70% by mass is more preferred, 90% by mass is further preferred, and 99% by mass is further preferred. , And 99.9% by mass is even better. On the other hand, the upper limit of the content may be substantially 100% by mass, may be 99% by mass, or may be 90% by mass.

The modified PVA (A) has a sulfonic acid group (-SO ₃ H) or a salt thereof (a salt of a sulfonic acid group, for example, -SO ₃ M: M is an alkali metal atom) in a side chain, and is bonded to the sulfonic acid group The modification amount of the aromatic ring of the sulfonic acid group or the salt thereof is 0.01 mol% or more and 10 mol% or less.

The modified PVA (A) is a polymer having a vinyl alcohol unit as a main repeating unit. The lower limit of the proportion of the vinyl alcohol units occupied by the totally repeating units in the modified PVA (A) is, for example, preferably 60 mol%, more preferably 70 mol%, and more preferably 80 mol%. On the other hand, the upper limit of the ratio of the vinyl alcohol unit is, for example, preferably 99.9 mol%, and more preferably 99 mol%.

The above-mentioned salt (salt of a sulfonic acid group) refers to a group in which a hydrogen ion of a sulfonic acid group (-SO ₃ H) is replaced with a cation such as a metal ion or an ammonium ion. Examples of the salt (salt of sulfonic acid group), based alkali metal salt (-SO ₃ M: M is an alkali metal atom) are preferred, sodium salt (-SO ₃ Na) is preferred.

Examples of the aromatic ring include a carbocyclic ring such as a benzene ring and a naphthalene ring, a heterocyclic ring such as a furan ring, and a pyridine ring, and a carbocyclic ring is more preferable, and a benzene ring is more preferable. The sulfonic acid group or a salt thereof is preferably bonded to the aromatic ring system through a sulfur atom of the sulfonic acid group. In this case, the sulfonic acid group or a salt thereof and the aromatic ring may be directly bonded via a sulfur atom of the sulfonic acid group, or may be linked through another bond (linking group). However, it is preferable that the sulfonic acid group or a salt thereof is directly bonded to the aromatic ring system.

As a method for introducing a sulfonic acid group or a salt thereof into the side chain of the vinyl alcohol polymer, as described later, the vinyl alcohol polymer (B) (hereinafter referred to as “PVA” (B) ") Method of acetalization. Therefore, the modified PVA (A) is preferably a structural unit having the following formula (I). In addition, the PVA (B) usually contains a trace amount of an alkali catalyst used in the saponification in the production step. Therefore, even if the aldehyde having a sulfonic acid group used in acetalization is not a salt, the sulfonic acid group of the obtained modified PVA (A) can be in a state of a salt such as an alkali metal salt.

In the above formula (I), X ¹ and X ² are each independently a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms or -Z-SO ₃ Y, and at least one of X ¹ and X ² is- Z-SO ₃ Y. Y is independently a hydrogen atom, a metal atom, or an ammonium group. Z is independently a single bond or a linking group.

Examples of the metal atom represented by Y include an alkali metal atom (such as a lithium atom, a sodium atom, and a potassium atom), and an alkaline earth metal atom (such as a calcium atom). Among them, from the viewpoint of the solubility of the obtained film and the like, Y is preferably a hydrogen atom and an alkali metal atom, more preferably a hydrogen atom and a sodium atom, and a further more preferable sodium atom. In addition, when Y is a divalent or more metal atom such as an alkaline earth metal atom, Y may form a crosslinked structure with two or more -SO ₃ ^- bonds.

Examples of the linking group represented by Z include, in addition to a divalent hydrocarbon group, -O-, -CO-, -COCO-, -CO (CH ₂ ) _m CO-, -CH (OH)-,- S-, -CS-, -SO-, -SO _2- , -NR ^1- , -CONR ^1- , -NR ¹ CO-, -CSNR ^1- , -NR ¹ CS-, -NR ¹ NR ¹ -,- _{-HPO 4 -, - Si (OR} 1) 2 -, - OSi (OR 1) 2 -, - OSi (OR 1) 2 O -, - Ti (OR 1) 2 -, - OTi (OR 1) 2 - , -OTi (OR ¹ ) ₂ O-, -Al (OR ¹ )-, -OAl (OR ¹ )-, -OAl (OR ¹ ) O-, and the like. Here, R ^{1 is} each independently an arbitrary substituent, and a hydrogen atom and an alkyl group are preferred. In addition, m is a natural number of 1-10. Examples of the divalent hydrocarbon group include divalent aliphatic hydrocarbon groups such as an alkylene group, an alkenyl group, and an alkynyl group; and divalent aromatic hydrocarbon groups such as a phenylene group and a naphthyl group. Some or all of the hydrogen atoms possessed by these hydrocarbons may be substituted with halogen atoms such as fluorine atom, chlorine atom, and bromine atom. The Z is preferably a single bond.

From the viewpoint of reactivity for acetalization, the above X ¹ and X ^{2 are} based on X ¹ being -Z-SO ₃ Y, X ² is a hydrogen atom, a halogen atom, a hydroxyl group, and a carbon number of 1 to 4 Alkyl or -Z-SO ₃ Y is preferred. It is speculated that the -Z-SO ₃ Y shown in the above X ¹ is bonded to an adjacent carbon atom relative to the aromatic ring carbon atom bonded to the aldehyde, and -Z-SO ₃ Y is used as an intramolecular acid catalyst. Plays a role, so the reactivity of aldehyde is further improved. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among them, a chlorine atom and a bromine atom are more preferable. The alkyl group having 1 to 4 carbon atoms may be linear or branched, and examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and secondary butyl. Etc. Among them, methyl and ethyl are preferred. X ² is more preferably a hydrogen atom, a chlorine atom, a hydroxyl group, a methyl group, or -SO ₃ Y, and a hydrogen atom is further more preferable.

In the modified PVA (A), the lower limit of the modification amount of the sulfonic acid group or its salt is 0.01 mol%, preferably 0.05 mol%, more preferably 0.1 mol%, and 0.2 mol%. Particularly preferred, 0.3 mole% is best. When the modification amount of the sulfonic acid group or a salt thereof is less than the above-mentioned lower limit, compared with PVA (B) before modification, the improvement of its water solubility is insufficient. On the other hand, the upper limit of the modification amount of the sulfonic acid group or a salt thereof is 10 mol%, preferably 7 mol%, more preferably 5 mol%, and particularly preferably 3 mol%. When the modification amount of the sulfonic acid group or a salt thereof is larger than the above-mentioned upper limit, the mechanical strength of a film or the like formed of a resin material becomes insufficient, and the initial solubility when the film is immersed in water may be high.

Here, the modification amount of the sulfonic acid group or its salt refers to the ratio of the total mol number of the sulfonic acid group and its salt with respect to the total number of mols of the repeating unit of the modified PVA (A). In addition, in this specification, the structure shown by -CR ₂ -CR ₂ -is set to 1 repeating unit. The above-mentioned Rs are each independently a hydrogen atom or an arbitrary substituent, and two Rs each contained in the same or different structural unit may be bonded. For example, the structural unit represented by the formula (I) is set to include two repeating units. On the other hand, a vinyl alcohol unit, a residual vinyl ester unit, a structural unit derived from another monomer, etc. are set to each contain one repeating unit. In other words, the structure corresponding to the monomer having a carbon-carbon double bond used for the polymerization is a repeating unit.

The modification amount of the sulfonic acid group or a salt thereof can be determined by ¹ H-NMR measurement of the resin material. For example, when a modified PVA (A) obtained by performing an acetalization reaction using sodium benzaldehyde-2-sulfonate as a main component is used as a resin material, the resin material is dissolved in DMSO-d ₆ , and ¹ H at 400 MHz is used. -NMR. The peak of the methine group from the vinyl alcohol unit belongs to 4.2 to 5.2 ppm (integral value α), and the peak of the benzene ring of sodium benzaldehyde-2-sulfonate belongs to 7.0 to 8.0 ppm (integral value β). The modified amount of the sulfonic acid group or its salt is calculated by the following formula.

Modification amount of sulfonic acid group or its salt (mol%) = ((β / 4) / α) × 100

The lower limit of the viscosity of the 4% by mass aqueous solution of the modified PVA (A) is preferably 2mPa‧s, 2.5mPa‧s is more preferable, and 3mPa‧s is even more preferable. On the other hand, the upper limit of the viscosity of the above 4% by mass aqueous solution is preferably 20 mPa · s, 15 mPa · s is more preferable, and 10 mPa · s is even more preferable. When the viscosity of the 4% by mass aqueous solution is less than the lower limit described above, the mechanical strength of the obtained film or the like tends to decrease. On the other hand, when the viscosity of the 4% by mass aqueous solution is larger than the upper limit described above, there is a tendency that the resin material gels by heating during the production of the resin material. The viscosity of the 4% by mass aqueous solution of this modified PVA (A) was measured under the conditions of a rotor speed of 60 rpm and a temperature of 20 ° C using a B-type viscometer. The B-type viscosity meter can be used, for example: B-type viscosity meter BLII (manufactured by Toki Sangyo Co., Ltd.), digital B-type viscosity meter BASE (trade name, manufactured by Atago Co., Ltd.), digital B-type viscosity meter PRO (product Name, Atago Co., Ltd.) and other commercially available products.

The lower limit of the degree of saponification of the modified PVA (A) is preferably 60 mol%, more preferably 65 mol%, 70 mol% is further better, and 80 mol% is further better. Also 85 mol% is even better. On the other hand, the upper limit of the degree of saponification of the modified PVA (A) is preferably 99 mol%, more preferably 98 mol%, and more preferably 97 mol%. By setting the saponification degree of the modified PVA (A) to be above the lower limit, it is possible to improve the water-soluble improvement effect more than the PVA (B) before the modification. In addition, by setting the degree of saponification of the modified PVA (A) to be equal to or less than the above-mentioned upper limit, the solubility of the obtained water-soluble film in the initial stage of immersion in water can be further suppressed. On the other hand, when the degree of saponification is greater than the above-mentioned upper limit, the modified PVA (A) cannot be produced industrially stably, and it is likely that film formation cannot be performed stably from such a modified PVA (A). The degree of saponification of the modified PVA (A) is measured by a method described in JIS-K6726-1994.

In the modified PVA (A), the lower limit of the block characteristics of the remaining vinyl ester units is preferably 0.55, more preferably 0.58, and still more preferably 0.6. By setting the block characteristics to be at least the above lower limit, it is possible to improve the effect of improving water solubility compared to PVA (B) before modification. In addition, the reason why the water solubility is improved due to the improvement of the block characteristics has not been determined. It is speculated that the crystallinity of the modified PVA (A) is reduced due to the decrease in the blockability of the remaining vinyl ester units, and as a result, the water solubility is improved. On the other hand, the upper limit of the block characteristics is preferably 1, more preferably 0.9, more preferably 0.85, and particularly preferably 0.8. A modified PVA (A) having a block characteristic larger than the above upper limit tends to be difficult to manufacture.

In addition, the above-mentioned block characteristics are numerical values representing the distribution of the residual ester (usually an alkoxycarbonyl group) and the hydroxyl group generated by saponification of the ester, and take a value between 0 and 2. 0 indicates that the residual ester or hydroxyl group is completely distributed, and the interactivity increases as the value increases, 1 indicates that the residual ester and hydroxyl group exist completely randomly, and 2 indicates that the residual ester and hydroxyl group completely exist. The above-mentioned residual ester means the ester (-OC (= O) -Q (Q represents CH ₂ contained in the vinyl ester monomer) contained in the vinyl ester unit in the modified PVA (A) obtained by saponification treatment. = Alkyl group other than CH-OC (= O)))). In other words, the block characteristics are numerical values representing the distribution of the remaining vinyl ester units and vinyl alcohol units. The block characteristics can be determined by ¹³ C-NMR measurement described later in the examples. When the modified PVA (A) contains repeating units other than vinyl ester units and / or vinyl alcohol units, the block characteristics are such that the vinyl ester units and / or vinyl alcohol units in the modified PVA (A) are continuous All parts are calculated as objects.

The above-mentioned block characteristics can be adjusted by the type of vinyl ester monomer, the saponification conditions such as catalyst and solvent, the heat treatment after saponification, and the like. Among them, when saponification is performed by a general method, the block characteristic is usually less than 0.55, but the block characteristic can be set to a value of 0.55 or more by the subsequent reaction under heating.

    (Inorganic salt)    

In the resin material of the present invention, the content of the inorganic salt is 100 ppm or less, preferably 50 ppm or less, more preferably 30 ppm or less, and even more preferably 10 ppm or less. In addition, "ppm" is a content ratio set on a mass basis. In addition, since 10 ppm is a measurement limit of a general analytical instrument, 10 ppm or less means that an inorganic salt is not substantially contained. When the content of the inorganic salt is more than 100 ppm, the effect of suppressing the solubility in the initial stage of immersion in water of a thin film made of a resin material becomes insufficient. In addition, the content of the inorganic salt means the content ratio of the inorganic salt occupied by the resin material. The inorganic salt does not include a salt of a sulfonic acid group of the modified PVA (A).

When the acetalization reaction of a vinyl alcohol polymer is performed in a solution, in order to facilitate the reaction, an inorganic catalyst such as sulfuric acid, hydrochloric acid, phosphoric acid or an ammonium salt acid catalyst is usually used to react the system. It is added so that pH becomes 5 or less. At this time, the acid catalyst remains as an inorganic salt in the obtained resin material even after a step of neutralizing with an alkaline substance after the reaction is completed. In the production method of the present invention described later, a sulfonic acid group or a salt thereof can be introduced into PVA (B) without substantially using an inorganic acid or a salt thereof as a catalyst. Therefore, an additional neutralization step is not required, and it can be easily obtained. A resin material that does not substantially contain an inorganic salt.

Examples of the inorganic salt include metal salts or ammonium salts of inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid. Examples of the metal salt include an alkali metal salt and an alkaline earth metal salt. Specific examples include sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, ammonium sulfate, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, ammonium chloride, sodium phosphate, potassium phosphate, magnesium phosphate, and phosphoric acid. Calcium, ammonium phosphate, etc.

As a measuring method of the content of the inorganic salt in the resin material of this invention, the X-ray fluorescence analysis method mentioned later in an Example is mentioned, for example.

    (Plasticizer)    

The water-soluble film of the preferred embodiment of the resin material of the present invention is required to withstand use strength or toughness even in a high-temperature and humid area or a cold area, and particularly requires impact resistance at low temperatures. For the purpose of improving impact resistance at low temperatures and improving solubility in water, the resin material of the present invention preferably contains a plasticizer. The plasticizer may be added during the melt-kneading described later, or may be added during the production of a water-soluble film.

The plasticizer is not particularly limited as long as it is generally used as a plasticizer of PVA, and examples thereof include glycerol, diglycerol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and propylene glycol. , Dipropylene glycol, hexanediol, neopentyl glycol, trimethylolpropane, neopentaerythritol, 1,3-butanediol, 2-methyl-1,3-propanediol, sorbitol, polyether polyvalent Polyols such as alcohols, polyether glycols, polyether triols, and xylitol; polyethers such as polyethylene glycol and polypropylene glycol; polyvinylamines such as polyvinyl pyrrolidone; N-methyl Ammonium compounds such as pyrrolidone and dimethylacetamide; compounds obtained by adding ethylene oxide and propylene oxide to polyhydric alcohols such as glycerol, neopentyl alcohol, and sorbitol. These may be used singly or in combination of two or more kinds. Among them, for the purpose of improving water solubility, glycerin, diglycerin, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, and 2-methyl-1,3-propanediol are also used. , Polyethylene glycol, or polyvinylpyrrolidone is preferred, especially from the viewpoint of inhibiting the water solubility of the film caused by the bleeding of the plasticizer, glycerol, diglycerol, and trimethylol are used. Propane, 2-methyl-1,3-propanediol, polyethylene glycol, or polyvinylpyrrolidone is even more preferred.

When polyethylene glycol is used as a plasticizer, the molecular weight of polyethylene glycol is not particularly limited, but from the viewpoints of compatibility with modified PVA (A) and reduction in water solubility due to suppression of exudation It is considered that the number average molecular weight (Mn) is preferably 100 to 1,000. The molecular weight of polyvinylpyrrolidone is also not particularly limited. From the viewpoint of compatibility with modified PVA (A), a mass average molecular weight (Mw) of 1,000 to 20,000 is preferred.

The lower limit of the content of the plasticizer is preferably 1 part by mass relative to 100 parts by mass of the modified PVA (A), more preferably 5 parts by mass, and even more preferably 10 parts by mass. On the other hand, the upper limit of the content of the plasticizer is preferably 60 parts by mass relative to 100 parts by mass of the modified PVA (A), more preferably 40 parts by mass, and even more preferably 20 parts by mass. By setting the content of the plasticizer to be above the lower limit described above, the effect caused by blending the plasticizer can be improved. On the other hand, by setting the content of the plasticizer to not more than the above upper limit, the mechanical properties and blocking resistance of the obtained film can be improved.

    (Other ingredients)    

The resin material of the present invention may further contain other components. However, the upper limit of the content of the components other than the modified PVA (A) and the plasticizer in the resin material of the present invention is preferably 10% by mass, 1% by mass is more preferable, and 0.1% by mass is further more preferable. The upper limit of the content of components other than the modified PVA (A) in the resin material of the present invention is preferably 10% by mass, more preferably 1% by mass, and even more preferably 0.1% by mass.

    (Use, etc.)    

The resin material of the present invention can be used in various applications. Examples are listed below but are not limited thereto.

(1) Use of vinyl chloride dispersant: dispersion stabilizer and dispersion aid for suspension polymerization of vinyl chloride and vinylidene chloride

(2) Coating agent use: sizing agent, fiber processing agent, leather finishing agent, paint, anti-fogging agent, metal corrosion inhibitor, galvanizing agent, antistatic agent

(3) Adhesives and adhesives: Adhesives, adhesives, rewettable adhesives, various adhesives, additives for cement and mortar

(4) Use of dispersion stabilizers: dispersion stabilizers for organic and inorganic pigments such as paints and adhesives, dispersion stabilizers for emulsion polymerization of various vinyl compounds, and post-emulsifiers for asphalt, etc.

(5) Paper processing applications: paper strength enhancers, oil resistance and solvent resistance agents, smoothness improvers, surface gloss improvement additives, fillers, barrier agents, light resistance additives, water resistance agents, dyes, color development Dispersant, Adhesion Improver, Adhesive

(6) Agricultural use: adhesives for pesticides, spreaders for pesticides, agricultural coatings, soil improvers, anti-erosion agents, dispersants for pesticides

(7) Medical and Cosmetics Applications: Granulating adhesives, coating agents, emulsifiers, adhesives, binding agents, film preparation substrates, film forming agents

(8) Viscosity adjuster use: thickener, rheology adjuster

(9) Use of agglutinating agent: agglutinating agent for suspended matter and dissolved matter in water, metal agglutinating agent

(10) Film use: polarizing film, barrier film, film for fiber product packaging, seed curing sheet, vegetative sheet, seed tape, hygroscopic film

(11) Uses of molded articles: fibers, pipes, tubes, leak-proof films, water-soluble fibers for chemical lace, sponges

(12) Use of resin raw materials: Raw materials for polyvinyl butyral, photosensitive resin raw materials, graft polymer raw materials, various gel raw materials

(13) Post-reaction use: post-reaction use with low-molecular organic compounds, high-molecular organic compounds, and inorganic compounds

Among them, the use of film is more preferable, and the use of film for unit packaging is more preferable. The resin material of the present invention is particularly suitable as a material for forming a water-soluble film described later. The water-soluble film can be a size of 40mm × 40mm, which is completely dissolved in 1 liter of water at 20 ° C.

The shape of the resin material of the present invention is not particularly limited, and may be a solid state such as a powder state, a granular state, or a liquid state. However, from the viewpoint of operability and the like, solid is more preferable, and granular is more preferable.

    <Manufacturing method of resin material>    

The resin material of the present invention can, for example, obtain a vinyl ester polymer by polymerizing a vinyl ester monomer; use an alkali catalyst in an alcohol solution to saponify the vinyl ester polymer to obtain PVA (B); and substantially PVA (B) obtained by mixing under heating without using an inorganic acid or a salt thereof as a catalyst is produced with an aldehyde having a sulfonic acid group or a salt thereof.

Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl dodecanoate, vinyl octadecanoate, and vinyl benzoate. Esters, trimethyl vinyl acetate, vinyl versatate, and the like. Among them, vinyl acetate is more preferable.

Examples of a method for polymerizing a vinyl ester monomer include known methods such as a block polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among these methods, a block polymerization method performed without a solvent and a solution polymerization method performed using a solvent such as alcohol are preferable. From the viewpoint of improving the effect of the present invention, it is based on the presence of a lower alcohol. A solution polymerization method in which polymerization is carried out is more preferred. As the lower alcohol, an alcohol having a carbon number of 3 or less is preferred, methanol, ethanol, n-propanol, and isopropanol are more preferred, and methanol is further more preferred. When a polymerization reaction is carried out by a block polymerization method or a solution polymerization method, the reaction method may be either a batch method or a continuous method.

Examples of the initiator used in the polymerization include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), and 2,2 ' -Azo-based initiators such as azobis (4-methoxy-2,4-dimethylvaleronitrile); organic peroxide-based initiators such as benzamidine peroxide and n-propyl peroxycarbonate Wait for well-known initiators. The polymerization temperature during the polymerization reaction is not particularly limited, and a range of 5 ° C to 200 ° C is appropriate.

When the vinyl ester monomer is polymerized, the copolymerizable monomer can be further copolymerized within a range that does not impair the gist of the present invention. Examples of such monomers include α-olefins such as ethylene, propylene, 1-butene, isobutylene, and 1-hexene; (meth) acrylic acid and its salts; methyl (meth) acrylate, and (meth) (Meth) acrylates such as ethyl acrylate; acrylamide derivatives such as N-methacrylamide and N-ethylacrylamide; N-methacrylamide and N-ethylmethacryl Derivatives such as methacrylamide; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether; vinyl ether Vinyl ethers containing hydroxyl groups, such as alcohol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether; allyl acetate; propyl allyl ether, butyl allyl ether Allyl ethers such as hexyl allyl ether; monomers having oxyalkylene; isopropenyl acetate; 3-buten-1-ol, 4-penten-1-ol, 5-hexene-1 -Alcohols, 7-octenen-1-ol, 9-decen-1-ol, 3-methyl-3-buten-1-ol, and other α-olefins containing hydroxyl groups; maleic acid, itaconic acid, Unsaturated dicarboxylic acids such as fumaric acid and their salts or their esters; ethyl sulfonic acid, allyl sulfonic acid Monomers having a sulfonic acid group such as methallylsulfonic acid, 2-propenylamine-2-methylpropanesulfonic acid; vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyldimethoxy Monomers having a silicon group, such as methylmethoxysilane and vinyltriethoxysilane. As the upper limit of the usage amount of these monomers, it also varies depending on the purpose and application used, and it is more preferable to be 20 mol%, and more preferably 10 mol% relative to the whole monomer.

In the saponification reaction of the vinyl ester polymer obtained in the above polymerization step, an alcohol addition decomposition or hydrolysis reaction using a conventionally known basic catalyst such as sodium hydroxide, potassium hydroxide, sodium methoxide, or the like can be applied. Examples of the solvent used in the saponification reaction include alcohols such as methanol and ethanol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; and aromatic hydrocarbons such as benzene and toluene. Etc. can be used individually or in combination of 2 or more types. Among them, it is convenient and preferable to use methanol or a mixed solution of methanol and methyl acetate as a solvent, and perform the saponification reaction in the presence of sodium hydroxide of an alkaline catalyst. By this method, PVA (B) can be obtained.

The block characteristics of the remaining vinyl ester units in the PVA (B) obtained by the saponification reaction are, for example, 0.2 or more and less than 0.55, and may be 0.4 or more and 0.5 or less. In addition, the amount of modification of the sulfonic acid group or its salt in PVA (B) (the ratio of the total mol number of the sulfonic acid group and its salt with respect to the total number of moles of the repeating unit in PVA (B)) It is preferably less than 0.01 mole%, more preferably less than 0.001 mole%, and also substantially 0 mole%.

The step of mixing PVA (B) and aldehyde having a sulfonic acid group or a salt thereof (hereinafter sometimes referred to as an abbreviation hereinafter) by heating under heating of 80 ° C. to 240 ° C. without using an inorganic acid or a salt thereof as a catalyst substantially. It is a "mixing step"), and a resin material containing a modified PVA (A) obtained by acetalizing PVA (B) with the aldehyde as a main component and an inorganic salt content of 100 ppm or less can be obtained. At this time, from the viewpoint of suppressing gelation during heating, the viscosity of the 4% by mass aqueous solution of PVA (B) is 20 mPa · s or less. The range of the ideal 4% by mass aqueous solution viscosity and saponification degree of PVA (B) is the same as the range of the above-mentioned modified PVA (A).

In this manufacturing method, since an inorganic acid or a salt thereof is not substantially used as a catalyst in the mixing step, a resin material having an inorganic salt content of 100 ppm or less can be efficiently obtained. In addition, "substantially not using an inorganic acid or a salt thereof as a catalyst" means that an inorganic acid or a salt thereof is not intentionally added as a catalyst in the mixing step.

The aldehyde having a sulfonic acid group or a salt thereof (a salt of a sulfonic acid group) is not particularly limited, and for example, a compound represented by the following formula (II) can be used.

In the above formula (II), the definitions and preferred ranges of X ¹ and X ^{2 are} the same as those in the above formula (I). Examples of the compound represented by the formula (II) include benzaldehyde-2-sulfonic acid, benzaldehyde-2,4-disulfonic acid, 4-chlorobenzaldehyde-2-sulfonic acid, and 4-methylbenzaldehyde 2-sulfonic acid, 4-hydroxybenzaldehyde-2-sulfonic acid, or salts thereof. Among these, benzaldehyde-2-sulfonic acid and benzaldehyde-2,4-disulfonic acid are more preferable from the viewpoint of availability. Examples of the salt include alkali metal salts, alkaline earth metal salts, and ammonium salts. Among them, alkali metal salts are preferred, and sodium salts are more preferred. That is, as a desirable aldehyde having a sulfonic acid group salt, examples include sodium benzaldehyde-2-sulfonate, disodium benzaldehyde-2,4-disulfonate, and the like.

The lower limit of the amount of the aldehyde having a sulfonic acid group or a salt thereof is preferably 0.1 parts by mass relative to 100 parts by mass of PVA (B), more preferably 0.5 parts by mass, and 1 part by mass further. Better. On the other hand, the upper limit of the amount of the aldehyde having a sulfonic acid group or a salt thereof is preferably 50 parts by mass relative to 100 parts by mass of PVA (B), and more preferably 40 parts by mass. The mass part is further more preferable.

The lower limit of the heating temperature is 80 ° C, preferably 100 ° C, more preferably 130 ° C, and even more preferably 150 ° C. On the other hand, the upper limit of the heating temperature is 240 ° C, preferably 230 ° C, more preferably 220 ° C, and still more preferably 210 ° C. In this case, it is preferable to mix PVA (B) and an aldehyde having a sulfonic acid group or a salt thereof in a molten state. When the heating temperature is less than the above-mentioned lower limit, the reaction does not proceed sufficiently, and a resin material containing as a main component a modified PVA (A) that satisfies the modified amount of the sulfonic acid group or its salt specified in the present invention cannot be produced. When the heating temperature is higher than the above upper limit, PVA (B) is decomposed, or a gel is generated. In addition, the molten state may be a state where at least it can be confirmed that PVA (B) is melting.

The time for mixing PVA (B) with an aldehyde having a sulfonic acid group or a salt thereof under heating is not particularly limited, and the lower limit of the mixing time is preferably 1 minute, 3 minutes is more preferable, and 4 minutes is further more preferable . On the other hand, the upper limit of the mixing time is preferably 3 hours, more preferably 2 hours, even more preferably 1 hour, and particularly preferably 30 minutes. By setting the mixing time to be at least the above lower limit, the reaction can be sufficiently advanced. By setting the mixing time to be equal to or less than the above upper limit, decomposition of PVA (B) and generation of gel can be suppressed.

The method of mixing PVA (B) with an aldehyde having a sulfonic acid group or a salt thereof is not particularly limited. For example, after dry blending using a belt blender, Henschel mixer, V-type blender, etc., A known mixing device or kneading device such as a kneading extruder, a single-axis or two-axis extruder, a mixing roll, and a Banbury mixer is used. Among them, a single-shaft or two-shaft extruder with sufficient kneading power is used, and the method of mixing in a molten state is preferable.

In the above mixing step, it is preferable to perform mixing in the absence of a solvent substantially. That is, a method of mixing a powder containing PVA (B) and a powder containing an aldehyde having a sulfonic acid group or a salt thereof to perform acetalization under the above-mentioned heating is preferable. At this time, depending on the heating temperature, the powder containing PVA (B) and the powder containing an aldehyde having a sulfonic acid group or a salt thereof may be mixed in a powder state or in a molten state, from the viewpoint of improving reactivity. It is preferable to mix in a molten state. According to the manufacturing method of the present invention, since mixing can be performed in the absence of a solvent substantially, a drying step such as removal of the solvent is not required, and the modified PVA (A) can be manufactured more easily. In addition, "in the absence of a solvent substantially" means that a solvent is intentionally not added to a mixture of PVA (B) and an aldehyde having a sulfonic acid group or a salt thereof.

In the above-mentioned mixing step, a plasticizer or the like may be further added to lower the melt-softening temperature. As the plasticizer, the aforementioned plasticizer can be used. The addition amount of the plasticizer is not particularly limited, and as a lower limit, it is preferably 3 parts by mass relative to 100 parts by mass of PVA (B), 5 parts by mass is more preferable, and 10 parts by mass is further more good. On the other hand, the upper limit of the amount of the plasticizer is preferably 40 parts by mass relative to 100 parts by mass of PVA (B), more preferably 30 parts by mass, and even more preferably 20 parts by mass. .

In the manufacturing method of the resin material, the PVA (B) is modified from the PVA (A) to the modified PVA (A) by passing through the above-mentioned mixing step. Compared with the block characteristics of the PVA (B), the The block characteristics are improved. The lower limit of the difference between the block characteristics of the residual vinyl ester units in PVA (B) and the block characteristics of the residual vinyl ester units in modified PVA (A) is preferably 0.05, more preferably 0.08, 0.1 is even better. The upper limit of the difference between the above-mentioned block characteristics is preferably 0.4, more preferably 0.35, and even more preferably 0.3. By setting the difference in the block characteristics of the remaining vinyl ester units to the above range, it is possible to obtain a film whose water solubility is further improved compared to a film obtained from a vinyl alcohol polymer before modification.

    <Water-soluble film>    

The water-soluble film formed by the resin material of the present invention is also one of the ideal embodiments of the present invention. The water-soluble film may be formed only of the resin material described above, or may further contain other components. In this water-soluble film, the content of the modified PVA (A) is not particularly limited, and may be more than 50% by mass, may be 60% by mass or more, and may be 70% by mass or more. The upper limit of the content of the modified PVA (A) in the water-soluble film may be substantially 100% by mass. The content of the ideal plasticizer in the water-soluble film is the same as the content of the ideal plasticizer in the resin material. Compared with the film containing PVA before modification, the water-soluble film of the present invention has sufficient water solubility, and at the same time, it can suppress the solubility in the initial stage of immersion in water.

The water-soluble film of the present invention may be blended with a surfactant as required. The type of the surfactant is not particularly limited, and may be any of a nonionic, anionic, cationic, and amphoteric surfactant, and a nonionic or anionic surfactant is preferred.

Examples of the nonionic surfactant include alkyl ether types such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; alkylphenyl ether types such as polyoxyethylene octylphenyl ether; and polyoxyethylene lauryl Alkyl ester types such as acid esters; alkyl amine types such as polyoxyethylene lauryl amino ether; alkyl amine types such as polyoxyethylene laurate amine; polypropylene glycol ether types such as polyoxyethylene polyoxypropylene ether; oil Alkylamine type such as acid diethanolamidine; allylphenyl ether type such as polyoxyallyl allylphenyl ether and the like. As nonionic surfactants, propylene glycol, diethylene glycol, monoethanolamine, alcohol ethoxylate, alkylphenol ethoxylate, tertiary acetylene glycol, alkanolamine, etc. can also be used. .

Examples of the anionic surfactant include carboxylic acid types such as sodium myristate, sodium palmitate, sodium stearate, sodium laurate, and potassium laurate; sulfate types such as sodium octosulfonate; lauryl phosphate, Phosphate types such as sodium lauryl phosphate; sulfonic acids such as sodium octyl sulfosuccinate and sodium dodecylbenzenesulfonate.

Examples of the cationic surfactant include amines such as laurylamine hydrochloride; quaternary ammonium salts such as polyethoxyamine and lauryltrimethylammonium chloride; pyridine such as laurylpyridine cationic chloride Cation salts, etc.

Examples of the amphoteric surfactant include alkyl betaines such as lecithin, alkylamine oxides, N-alkyl-N, N-dimethylammonium betaine, and sulfobetaines.

These surfactants can be used singly or in combination of two or more kinds.

The lower limit of the content of the surfactant in the water-soluble film of the present invention is preferably 0.01 parts by mass, more preferably 0.1 parts by mass, and 0.2 parts by mass relative to 100 parts by mass of the modified PVA (A). Further better. On the other hand, the upper limit of the content of the surfactant is preferably 10 parts by mass, more preferably 5 parts by mass, and even more preferably 2 parts by mass. By setting the content of the surfactant to the above lower limit or higher, there is a tendency that the metal surface such as a drum of a film forming apparatus and the peelability of the film formed through the film are improved, and it becomes easy to manufacture. When the content of the surfactant is set to be equal to or less than the above-mentioned upper limit, the surface of the film is eluted and the film sticking is suppressed, and the workability tends to be improved.

The water-soluble film of the present invention may be blended with saccharides as needed. Examples of the saccharides include monosaccharides, oligosaccharides, polysaccharides, and chain sugar alcohols. Examples of the monosaccharides include glucose. Examples of the oligosaccharide include galactooligosaccharide, isomalto-oligosaccharide, xylo-oligosaccharide, soybean oligosaccharide, nigero oligosaccharide, lacto-oligosaccharide, and fructooligosaccharide. Examples of polysaccharides include starch, cellulose, chitin, chitosan, hemicellulose, pectin, polytriglucose, agar, alginic acid, carrageenan, dextrin, trehalose, melons Gum, Sanxian Gum, Gum Arabic, etc. Examples of the chain sugar alcohols include tetrabutanols having 4 carbon atoms, such as threitol and erythritol; pentaerythritols having 5 carbon atoms, such as arabitol and xylitol; iditol, hemihydrin Hexanols having 6 carbon atoms, such as lactitol, mannitol, and sorbitol. Examples of the starch include crude starch such as corn and potato, and processed starch (dextrin, oxidized starch, etherified starch, and cationized starch) which are subjected to physical or chemical treatment. These saccharides can be used singly or in combination of two or more kinds. By blending saccharides, the water solubility and biodegradability of the film are further improved, the boric acid ion resistance is improved, and the cold water solubility after drug packaging can be suppressed from decreasing. In particular, it can be used to suppress the degradation of vinyl alcohol polymers by packaging Chlorine-based substances, etc.) reduce the solubility of cold water. From the viewpoint of good cold water solubility of the film when sugar is added, starch is particularly preferred among the sugars.

The lower limit of the content of saccharides in the water-soluble film of the present invention is preferably 1 part by mass relative to 100 parts by mass of modified PVA (A), 2 parts by mass is preferable, and 3 parts by mass is more good. On the other hand, the upper limit of the saccharide content is preferably 100 parts by mass, more preferably 90 parts by mass, and even more preferably 80 parts by mass. By setting the content of sugars to be above the above lower limit, the water solubility and biodegradability of the film can be further improved. On the other hand, by setting the content of sugars to be equal to or less than the above-mentioned upper limit, the impact resistance of the film at a low temperature is improved, and it is difficult to break the bag.

The water-soluble film of the present invention may be blended with an inorganic filler as required. Examples of the inorganic filler include silica, heavy, light, or surface-treated calcium carbonate, aluminum hydroxide, aluminum oxide, titanium oxide, diatomaceous earth, mica, barium sulfate, calcium sulfate, and stearic acid. Salt (magnesium stearate, etc.), zeolite, zinc oxide, silicic acid, silicate, mica, magnesium carbonate, layered silicate, kaolin, polykaolin, pyrophyllite, sericite and other clays, talc, etc. These inorganic fillers can be used singly or in combination of two or more kinds. Among these, it is more preferable to use talc from the viewpoint of dispersibility with respect to the modified PVA (A). The average particle diameter of the inorganic filler is preferably 1 μm or more from the viewpoint of anti-blocking properties of the film, and 10 μm or less from the viewpoint of dispersibility with respect to the modified PVA (A). Better. In order to satisfy both the anti-blocking properties of the film exhibited by blending inorganic fillers and the dispersibility of inorganic fillers to modified PVA (A), an inorganic particle having an average particle diameter of about 1 to 7 μm is used. Fillers are more preferred. The average particle diameter can be measured by a laser diffraction particle size distribution measuring device (SALD-2100: manufactured by Shimadzu Corporation) using a 0.2% by mass sodium hexametaphosphate aqueous solution as a dispersion medium.

The lower limit of the content of the inorganic filler in the water-soluble film of the present invention is a modification with respect to 100 parts by mass of the film from the viewpoints of the anti-blocking property of the film and the dispersibility of the inorganic filler to the modified PVA (A). PVA (A) is more preferably 0.5 parts by mass, more preferably 0.7 parts by mass, and even more preferably 1 part by mass. The upper limit of the content of the inorganic filler is 20 from 100 parts by mass of the modified PVA (A) in terms of the anti-blocking property of the film and the dispersibility of the inorganic filler to the modified PVA (A). The mass part is more preferable, 15 mass part is more preferable, and 10 mass part is further more preferable.

The water-soluble film of the present invention may be blended with an antioxidant as required. Examples of the antioxidant include ascorbic acid, tocopherol, dibutylhydroxytoluene, butylhydroxymethoxybenzene, citric acid, carbamic acid, sorbic acid, sodium sorbate, sodium erythorbate, propyl gallic acid, sodium sulfite, Sodium metabisulfite, 2,5-di-tertiary butyl hydroquinone, 2,6-di-tertiary butyl-p-cresol, 4,4'-sulfide bis- (6-tertiary butyl phenol), 2 , 2'-methylenebis- (4-methyl-6-tertiarybutylphenol), 3- (3,5-di-tertiarybutyl-4-hydroxyphenyl) propanoic acid octadecyl ester ( Irganox 1076), 4,4'-sulfurized bis (3-methyl-6-tert-butylphenol) and the like. Antioxidants that are acids can also be used in the form of their salts. Moreover, thiosulfate, iodide, nitrite, etc. can also be used as an antioxidant.

The lower limit of the content of the antioxidant in the water-soluble film of the present invention is preferably 0.01 parts by mass, more preferably 0.1 parts by mass, and 0.5 parts by mass relative to 100 parts by mass of the modified PVA (A). Better. On the other hand, the upper limit of the content of the antioxidant is preferably 10 parts by mass, more preferably 5 parts by mass, and even more preferably 3 parts by mass. By setting the content of the antioxidant to the above range, the oxidation resistance of the film can be fully exerted.

The water-soluble film of the present invention may be blended with a lubricant and a release agent as required. Examples of the lubricant and release agent include fatty acids and their salts, aliphatic alcohols, aliphatic esters, fatty amines, aliphatic amines, acetates, and aliphatic amines. The content of the lubricant and release agent in the water-soluble film of the present invention is preferably 0.02% by mass or more and 1.5% by mass or less.

The water-soluble film of the present invention may be blended with a defoaming agent as required. Examples of the defoaming agent include hydrophobic silica such as particulate silica. Examples of commercially available defoamers include "Foam Blast 327", "Foam Blast UVD", "Foam Blast 163", "Foam Blast 269", "Foam Blast 338", and "Foam Blast" from Emerald Performance Materials. 290 "," Foam Blast 332 "," Foam Blast 349 "," Foam Blast 550 "," Foam Blast 339 "(Foam Blast is a registered trademark), etc. The content of the defoaming agent in the water-soluble film of the present invention is preferably 0.01 to 0.5 parts by mass with respect to 100 parts by mass of the modified PVA (A).

The water-soluble film of the present invention may be blended with an aversive agent as needed. Examples of the aversive agent include bittering agents such as denaturing ammonium salt, sucrose octaacetate, quinine, and flavonoids, and astringent agents such as capsaicin, piperine, and resin toxin. The content of the aversive agent in the water-soluble film of the present invention is preferably from 0.01% by mass to 5% by mass.

The water-soluble film of the present invention may also contain moisture. The water content in the water-soluble film of the present invention may be, for example, 4% by mass or more and 10% by mass or less. The water content can be measured by Carr-Fisher titration.

The water-soluble film of the present invention is suitably blended with a colorant, a perfume, an extender, a defoaming agent, a release agent, an ultraviolet absorber, a plasticizer, a compatibilizer, a lubricant, a detackifier, and a bleaching agent even if necessary. (Sodium bisulfite, sodium metabisulfite) and other additives are also acceptable. In addition, as an additive, PVA (modified PVA or unmodified PVA) and carboxymethyl fiber different from the modified PVA (A) described above may be blended within a range that does not impair the effects of the present invention as needed. Cellulose, polyacrylamide, polyacrylic acid or its salt, methyl cellulose, hydroxymethyl cellulose, polyacrylate, polymethacrylate, polyvinylpyrrolidone, polyethyleneimine, polyalkylene oxide , Cellulose ether, cellulose ester, cellulose amine, polyvinyl acetate, polycarboxylic acid or its salt, polyurethane, polyamide, gelatin, methyl cellulose, ethyl cellulose, hydroxyethyl Water-soluble polymers such as cellulose, hydroxypropylmethyl cellulose, and maltodextrin. In particular, from the viewpoint of improving the water solubility of the film, it is preferable to blend carboxymethyl cellulose of a low viscosity type. The upper limit of the content of these additives in the water-soluble film is, for example, 50% by mass, 20% by mass, 15% by mass, 10% by mass, 5% by mass, 3% by mass, or 1% by mass. On the other hand, the lower limit of the content of these additives is, for example, 0.01% by mass, 0.1% by mass, 1% by mass, or 5% by mass.

The content of the inorganic salt in the water-soluble film of the present invention is preferably 100 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and still more preferably 10 ppm or less. Thereby, the solubility at the initial stage of immersion in water can be more sufficiently suppressed.

When manufacturing the water-soluble film of the present invention, the manufacturing raw materials may be prepared by blending other components with the aforementioned resin material of the present invention as required to dissolve or disperse them in a solvent in a stirring tank, or It is prepared by mixing in a known method such as a method of melt-kneading in an extruder.

The method for producing the water-soluble film of the present invention is not particularly limited, and it can be produced by a known method such as a casting method or a melt extrusion method. For example, the aforementioned resin material of the present invention and various additives (for example, surfactants, sugars) as required are dissolved in an aqueous solvent (for example, water), the resulting solution is allowed to stand on a smooth casting surface, and the aqueous solvent is evaporated. Then, peeling from the cast surface, a transparent and uniform water-soluble film can be obtained. The aqueous solvent is preferably water. The cast surface may be any material as long as it is smooth and hard such as steel, aluminum, glass, polymer (for example, polyolefin, polyethylene, polyamide, polyvinyl chloride, polycarbonate, polycarbonate, etc.) By. The evaporation rate of the aqueous solvent can be increased by heating the casting surface, or exposing the deposited solution to, for example, heated air or infrared rays.

The lower limit of the average thickness of the water-soluble film of the present invention is preferably 10 μm, more preferably 20 μm, and more preferably 30 μm. On the other hand, the upper limit of the average thickness is preferably 200 μm, more preferably 150 μm, and even more preferably 120 μm. By setting the average thickness to the above range, the strength, water solubility, solubility in the initial stage of immersion in water, and the like can be more balanced.

In order to improve the anti-blocking property of the water-soluble film of the present invention, the surface of the water-soluble film can be flattened as required, the water-soluble film can be coated with anti-blocking powder such as silicon dioxide or starch, and embossed. deal with. The flattening of the roll on the surface of the film can be carried out by forming fine unevenness on the roll which the film contacts before drying before forming the film. The embossing process is generally carried out by using an embossing roller and a rubber roller while applying heat or pressure after the film is formed. The coating powder has a large anti-blocking effect, but it may not be used due to the use of the film. Therefore, it is better to perform roll flattening or embossing. From the viewpoint of the size of the anti-blocking effect, it is based on the Roll flattening is particularly good.

Since this water-soluble film has sufficient water solubility and can suppress the solubility in the initial stage of immersion in water, it is useful in a wide range of fields such as pharmaceutical packaging materials and sanitary materials. The medicine is not particularly limited, and examples thereof include lotions for clothing, bleaching agents, pesticides (for example, Bordeaux agent (active ingredient: basic copper sulfate)), and the like. The form of the drug is not particularly limited, and may be a liquid or a solid (for example, powder, granule, block, etc.). The water-soluble film of the present invention is particularly suitable as a film for unit packaging.

    [Example]    

The following examples are used to explain the present invention more specifically. In the following, unless otherwise specified, "part" and "%" mean quality standards.

    [Viscosity of 4% by mass aqueous solution of PVA]    

The viscosity of a 4% by mass aqueous solution of PVA (including modified PVA) was measured using a B-type viscometer BLII (manufactured by Toki Sangyo Co., Ltd.) at a rotor speed of 60 rpm and a temperature of 20 ° C.

    [Saponification degree of PVA]    

The degree of saponification of PVA (including modified PVA) is determined in accordance with the method described in JIS-K6726-1994.

    [Modification amount of sulfonic acid group or salt thereof in modified PVA (A)]    

The modification amount of the sulfonic acid group or a salt thereof in the modified PVA (A) was determined by the method using ¹ H-NMR described above.

    [PVA block characteristics]    

The block characteristics of the residual vinyl ester units of PVA (including modified PVA) are for samples obtained by dissolving PVA in a heavy water / deuterated methanol mixed solvent, and performing ¹³ C at a measurement temperature of 70 ° C and a cumulative number of 18,000 times. -NMR measurement was performed by analyzing the three peaks of the two-unit chain structure (dyad) appearing in the methylene region, and was obtained from the integrated value of the peaks. The three peaks are equivalent to the carbon atom sandwiched between the main chain of the residual ester (-OC (= O) -Q (Q has the same meaning as above)) and the main chain of the hydroxyl chain. A methylene carbon between carbon atoms; a methylene carbon sandwiched between a carbon atom bonded to the main chain of the residual ester and a carbon atom close to the carbon atom and bonded to the main chain of the residual ester; and A methylene carbon sandwiched between a carbon atom bonded to a main chain of a hydroxyl group and a carbon atom near the carbon atom and bonded to a main chain of the hydroxyl group. The measurement method and calculation method are described in Poval (Polymer Society, 1984, pp. 246-249) and Macromolecules, 10, 532 (1977).

    [Content of inorganic salt in resin material]    

The content of the inorganic salt in the resin material was measured using an X-ray fluorescence analyzer (manufactured by Rigaku Co., Ltd., ZSX Primus μ) for the content of sodium chloride (NaCl). In addition, in the resin materials obtained in Examples and Comparative Examples described later, inorganic salts other than sodium chloride were not detected in the measurement by the X-ray fluorescence analyzer.

    [Evaluation method for improvement of water solubility of film]    

The resin materials obtained in Examples and Comparative Examples described later were dissolved in water to prepare a 10% by mass aqueous solution of the resin material. This aqueous solution was cast and dried at 20 ° C to obtain a film having a thickness of 76 µm. The film was cut into a square of 40 mm × 40 mm, and it was sandwiched in a single frame of a slide. In addition, a 1-liter glass beaker with a capacity of 1 liter of distilled water was set in a thermostatic bath adjusted to 20 ° C, and stirred at 250 rpm using a 5 cm rotor. After the distilled water in the beaker became 20 ° C, the above-mentioned slide single-piece outer frame was immersed in cold water under stirring to start the measurement of water solubility. At this time, the dissolved state of the film was visually observed, and the time δ (seconds) until the film formed of the resin material was completely dissolved was measured. In addition, a 76 μm-thick film of PVA (B) before modification was also prepared in the same method, and the time γ (seconds) until the film was completely dissolved in the obtained PVA (B) film was measured by the same method. From the difference between γ (second) and δ (second), evaluation was performed using the following criteria.

A: 30 seconds or more

B: more than 20 seconds and less than 30 seconds

C: more than 10 seconds and less than 20 seconds

D: less than 10 seconds

    [Evaluation method of initial insolubility of film]    

A 40 mm × 40 mm square test piece was produced by the same method as described above, and its mass (film quality before immersion) was measured. A 1-liter glass beaker filled with distilled water at a water temperature of 20 ° C was prepared, and a test piece was immersed in the beaker for 30 seconds. After 30 seconds, the film was taken out from the beaker, and after excess water was carefully sucked off with a filter paper, the film was dried at 105 ° C. for 3 hours, and the quality of the dried film was measured. The film residual after immersion was calculated using the following formula as the mass change before and after immersion in water, and was evaluated using the following criteria in accordance with the ratio of the film residual.

Film residual after immersion (%) = film quality after drying / film quality before immersion

A: 95% or more

B: Above 90% and less than 95%

C: above 80% and less than 90%

D: less than 80%

    [Example 1]    

100 parts by mass of 4 mass% aqueous solution with a viscosity of 5 mPa‧s, a saponification degree of 74 mole%, and a PVA (B) with a block characteristic of 0.43 of residual vinyl ester units and 3.8 parts by mass of benzaldehyde-2-sulfonic acid Sodium is obtained as an aldehyde having a sulfonic acid group or a salt thereof to obtain a mixture. In addition, the PVA (B) is a product obtained by saponifying a vinyl ester polymer using an alkali catalyst (the same applies hereinafter). The obtained mixture was melt-kneaded, and then cooled to obtain pellets of a resin material containing a modified PVA (A) having a sulfonic acid group salt introduced into a side chain as a main component. The melt-kneading conditions are shown below. Specifically, the modified PVA (A) in the obtained resin material has a structural unit represented by the above formula (I), X ¹ is -SO ₃ Na, and X ² is a hydrogen atom. The content of the inorganic salt in the obtained resin material was less than 10 ppm, the viscosity of a 4% by mass aqueous solution of modified PVA (A) was 4.5 mPa · s, the degree of saponification was 74 mole%, and the modification amount of the sulfonic acid group or its salt was The block characteristics of 0.5 mol% and the remaining vinyl ester units were 0.70. The improvement of the water solubility of the film and the evaluation of the initial insolubility were performed by the above method. The results are shown in Table 1.

    (Melt-kneading conditions)    

Installation: "Labo Plastomill 4C150" by Toyo Seiki

Kneading temperature: 180 ℃

Mixing time: 5 minutes

    [Examples 2 to 4, and 6]    

A modified PVA (A ) A resin material as a main component. About the obtained resin material, the improvement of the water solubility and the initial insolubility of the film were evaluated by the same method as in Example 1. The results are shown in Table 1.

    [Example 5]    

In addition to changing the type of PVA (B) used, the amount of the aldehyde containing a sulfonic acid group or a salt thereof, and the melting kneading temperature as shown in Table 1, further adding 100 parts by mass of PVA (B) during melt kneading. A resin material containing modified PVA (A) as a main component was produced in the same manner as in Example 1 except that polyethylene glycol (number-average molecular weight = 400) was used as a plasticizer. About the obtained resin material, the improvement of the water solubility and the initial insolubility of the film were evaluated by the same method as in Example 1. The results are shown in Table 1.

    [Comparative Example 1]    

A 100% by mass PVA (B) having a viscosity of 8 mPa · s, a saponification degree of 88 mol%, and a block characteristic of the remaining vinyl ester unit of 0.52 was used to prepare a 10% by mass aqueous solution while maintaining the temperature of the aqueous solution At 50 ° C, 5.3 parts by mass of sodium benzaldehyde-2-sulfonate was added and carefully stirred, and then 1.0 N hydrochloric acid was added so that the pH of the aqueous solution became 2.0. After maintaining in this state for 6 hours, after reacting, sodium hydroxide was added to neutralize. The obtained reaction product is purified to obtain a resin material containing modified PVA (A) as a main component. The content of the inorganic salt in the obtained resin material was 300 ppm, the viscosity of a 4% by mass aqueous solution of modified PVA (A) was 8 mPa · s, the degree of saponification was 92 mol%, and the modification amount of the sulfonic acid group or its salt was 0.5. The block characteristics of the mole% and the remaining vinyl ester units were 0.52. About the obtained resin material, the improvement of the water solubility of a film and the initial solubility were evaluated by the same method as Example 1. The results are shown in Table 1.

    [Comparative Example 2]    

A resin material was produced in the same manner as in Example 1 except that PVA (B) and sodium benzaldehyde-2-sulfonate were melt-kneaded, and sodium chloride was added so that the content of the inorganic salt became 150 ppm. About the obtained resin material, the improvement of the water solubility and the initial insolubility of the film were evaluated by the same method as in Example 1. The results are shown in Table 1.

    [Comparative Example 3]    

Except that the type of PVA (B) used and the amount of aldehyde having a sulfonic acid group or a salt thereof were changed as shown in Table 1, an attempt was made to modify PVA (A) in the same manner as in Example 1. However, PVA (B) The 4% by mass aqueous solution had a viscosity of greater than 20 mPa · s, and therefore gelled during melt-kneading, and no modified PVA (A) was obtained.

From the results in Table 1, the water-soluble film formed from the resin material satisfying the requirements of the present invention has a sufficiently improved water solubility compared to the PVA (B) before modification, and at the same time can suppress the initial immersion in water. Solubility. On the other hand, as in Comparative Examples 1 and 2, when the content of the inorganic salt in the resin material is more than 100 ppm, the solubility in the initial stage of immersion in water cannot be suppressed. In addition, from the results of the examples and comparative examples, it can be seen that the water-soluble film obtained from a resin material containing a modified PVA (A) having a block characteristic of 0.55 or more is more water-soluble than the PVA (B) before modification. Sex has been significantly improved.

    [Industrial availability]    

The resin material of the present invention can be suitably used as a material such as a water-soluble film.

Claims (11)

    A resin material comprising a modified vinyl alcohol polymer (A) as a main component, wherein the modified vinyl alcohol polymer (A) has a sulfonic acid group or a salt thereof in a side chain, and is bonded to In the aromatic ring of the sulfonic acid group or a salt thereof, the modification amount of the sulfonic acid group or a salt thereof in the modified vinyl alcohol polymer (A) is 0.01 mol% or more and 10 mol% or less, and an inorganic salt The content is 100 ppm or less.         The resin material according to claim 1, wherein the salt is an alkali metal salt.         For example, the resin material of claim 1 or 2, wherein the 4 mass% aqueous solution of the modified vinyl alcohol polymer (A) has a viscosity of 2 mPa · s or more and 20 mPa · s or less.         For example, the resin material of claim 1 or 2, wherein the saponification degree of the modified vinyl alcohol polymer (A) is 60 mol% or more and 99 mol% or less.         The resin material according to claim 1 or 2, wherein the block characteristics of the remaining vinyl ester units of the modified vinyl alcohol polymer (A) are 0.55 or more and 1 or less.         The resin material according to claim 1 or 2, further comprising a plasticizer.         A method for producing a resin material, which is the method for producing a resin material according to any one of claims 1 to 6, comprising: substantially not using an inorganic acid or a salt thereof as a catalyst, but at 80 ° C to 240 ° C A step of mixing a 4% by mass aqueous solution of a vinyl alcohol polymer (B) having a viscosity of 20 mPa · s or less and an aldehyde having a sulfonic acid group or a salt thereof under heating.         The method for producing a resin material according to claim 7, wherein in the mixing step, the vinyl alcohol polymer (B) and the aldehyde having a sulfonic acid group or a salt thereof are mixed in a molten state.         The method for manufacturing a resin material as claimed in claim 7 or 8, wherein in the mixing step, mixing is performed in the absence of a solvent substantially.         The method for producing a resin material according to claim 7 or 8, wherein the block characteristics of the remaining vinyl ester units in the vinyl alcohol polymer (B) and the residues in the modified vinyl alcohol polymer (A) The difference of the block characteristics of a vinyl ester unit is 0.05 or more and 0.4 or less.         A water-soluble film formed of a resin material according to any one of claims 1 to 6.