Ionomer resin particulate production method

Abstract

The present invention pertains to an ionomer resin particulate production method comprising a step for obtaining a porous particulate by extruding a mixture containing an ionomer resin and a solvent and cooling the extruded mixture to solidify a crude ionomer resin in the mixture. The crude ionomer resin includes a (meth)acrylic acid unit (A), a neutralized (meth)acrylic acid unit (B), and an ethylene unit (C). The total contained amount of said unit (A) and said unit (B) is 6-10 mol% with respect to all monomer units forming the crude ionomer resin. The porosity of said particulate is 60% or more.

Description

Method for producing ionomer resin granules

[0001] This patent application claims priority under the Paris Convention to Japanese Patent Application No. 2021-123194 (filing date: July 28, 2021), the entire contents of which are incorporated herein by reference. The present invention relates to a method for producing ionomer resin granules, porous ionomer resin granules, a resin sheet containing one or more layers containing the ionomer resin granules as a resin component, a laminated glass interlayer film made of the resin sheet, and laminated glass having the laminated glass interlayer film.

[0002] One known method for producing ionomer resins is a method that uses an ethylene-(meth)acrylic acid ester copolymer as a raw material and includes a step of saponifying the copolymer (hereinafter also referred to as the "EMMA saponification method") (see, for example, Patent Documents 1 to 3). This method has the advantage of not requiring corrosion-resistant equipment, whereas other methods for producing ionomer resins that include a copolymerization step of ethylene and (meth)acrylic acid (see, for example, Patent Document 4) require corrosion-resistant equipment. Furthermore, the EMMA saponification method allows the production of ionomer resins with a variety of copolymer compositions.

[0003] Japanese Patent Publication No. 60-240704 Japanese Patent No. 5554477 Japanese Patent Publication No. 63-270709 U.S. Patent No. 8,399,096

[0004] However, the inventors' investigations revealed that the EMMA saponification process involves a saponification reaction using an alkali and a demetallization reaction using an acid. This salt is generated by the neutralization reaction between the alkali and the acid, and the generated salt can reduce the transparency of the ionomer resin, particularly when the ionomer resin absorbs water. Therefore, the inventors attempted to remove the salt generated by the above reactions from the ionomer resin by adding a poor solvent to the reaction solution after the saponification reaction and the demetallization reaction to precipitate the ionomer resin (hereinafter referred to as the reprecipitation method). However, the reprecipitation method sometimes fails to sufficiently remove the salt, and the resulting ionomer resin is in a powder form, making it difficult to handle. Furthermore, the inventors investigated a method for obtaining a granular ionomer resin from the reaction solution after the saponification reaction and the demetallization reaction in order to improve the handleability of the resulting ionomer resin. However, they found it difficult to sufficiently remove the salt from the resulting granules.

[0005] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing ionomer resin granules that are excellent in transparency and ease of handling by improving the removal of salts formed in the EMMA saponification method.

[0006] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention. That is, the present invention provides the following preferred embodiments.

[0007] [1] A method for producing ionomer resin granules, comprising the steps of extruding a mixture containing a crude ionomer resin and a solvent, cooling the extruded mixture, and solidifying the crude ionomer resin in the mixture to obtain porous granules, wherein the crude ionomer resin contains (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), and ethylene units (C), the total content of the units (A) and the units (B) being 6 to 10 mol % based on all monomer units constituting the crude ionomer resin, and the porosity of the granules being 60% or more. [2] The method according to [1], wherein the extruded mixture is cooled by contacting the extruded mixture with a poor solvent. [3] The method according to [1] or [2], wherein the median pore diameter of the granules is 0.05 to 1.2 μm. [4] The method according to any one of [1] to [3], wherein the granules are pellets having a size of 1 to 8 mm. [5] The method according to any one of [1] to [4], wherein the crude ionomer resin further contains (meth)acrylic acid ester units (D), and the total content of the units (A), (B), and (D) is 6 to 10 mol % based on all monomer units constituting the crude ionomer resin. [6] The method according to any one of [2] to [5], wherein the poor solvent is water, an alcohol, or a mixed solvent thereof. [7] The method according to any one of [1] to [6], further comprising a step of washing the obtained porous granules with a washing liquid. [8] The method according to [7], wherein the washing liquid is water, an alcohol, or a mixed solvent thereof. [9] The method according to any one of [1] to [8], wherein the content of salts of strong acids and strong bases in the ionomer resin granules is 1000 mg / kg or less.

[10] The method according to any one of [1] to [9], wherein an ethylene-(meth)acrylic acid ester copolymer (X) is used as a raw material.

[11] A porous ionomer resin granule having a porosity of 60% or more.

[12] The porous ionomer resin granule according to

[11] , which is in the form of pellets having a size of 1 to 8 mm.

[13] The porous ionomer resin granule according to

[11] or

[12] , which has a median pore diameter of 0.05 to 1.2 μm.

[14] The porous ionomer resin granules according to any one of

[11] to

[13] , wherein the content of the salt formed from a strong acid and a strong base is 1000 mg / kg or less.

[15] A resin sheet comprising one or more layers containing the porous ionomer resin granules according to any one of

[11] to

[14] as a resin component.

[16] A laminated glass interlayer film comprising the resin sheet according to

[15] .

[17] A laminated glass having two glass plates and the laminated glass interlayer film according to

[16] disposed between the two glass plates.

[0008] According to the present invention, it is possible to provide a method for producing ionomer resin granules that are excellent in transparency and handleability by improving the removal of salts formed in the EMMA saponification method.

[0009] FIG. 1 is a conceptual diagram showing the X-axis length (Lx), Y-axis length (Ly), and Z-axis length (Lz) of a pellet used to calculate the pellet size, and the right side of FIG. 1 is a plan view of the pellet shown in the left side of FIG. 1 as viewed from the X-axis direction.

[0010] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0011] [Method for producing ionomer resin granules] The method for producing ionomer resin granules of the present invention includes a step of extruding a mixture containing a crude ionomer resin and a solvent, cooling the extruded mixture, and solidifying the crude ionomer resin in the mixture to obtain porous granules (hereinafter also referred to as "step (I)"), wherein the crude ionomer resin contains (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), and ethylene units (C), the total content of the units (A) and the units (B) being 6 to 10 mol % based on all monomer units constituting the crude ionomer resin, and the porosity of the granules being 60% or more.

[0012] The present inventors have investigated methods for removing salts generated by the saponification and demetallization reactions from crude ionomer resins produced by the EMMA saponification method. They found that by forming the crude ionomer resin into a porous body, salts can be removed not only from the resin surface but also from the interior of the resin through the pores, thereby improving salt removability. The present inventors then conducted further research, focusing on the relationship between the porosity of the porous body and salt removability. As a result, they found that by forming the crude ionomer resin into porous granules with a porosity of 60% or more, salts in the resin can be sufficiently removed, resulting in ionomer resin granules with excellent transparency and handleability. Therefore, when ionomer resin granules are produced by a method including step (I), salts in the resin can be easily removed, resulting in ionomer resin granules with excellent transparency and handleability. The present inventors also found that the method of the present invention can reduce the amount of solvent used compared to the reprecipitation method.

[0013] <Step (I)> Step (I) is a step of extruding a mixture containing a crude ionomer resin and a solvent, cooling the extruded mixture, and solidifying the crude ionomer resin in the mixture to obtain porous granules having a porosity of 60% or more.

[0014] (Crude Ionomer Resin) The crude ionomer resin in step (I) contains (meth)acrylic acid units (A), (meth)acrylic acid neutralized product units (B), and ethylene units (C), and the total content of the units (A) and the units (B) is 6 to 10 mol% based on all monomer units constituting the crude ionomer resin. In this specification, the term "unit" means a "structural unit derived from," and for example, a (meth)acrylic acid unit refers to a structural unit derived from (meth)acrylic acid, a (meth)acrylic acid neutralized product unit refers to a structural unit derived from a (meth)acrylic acid neutralized product, and an ethylene unit refers to a structural unit derived from ethylene. Furthermore, in this specification, "(meth)acrylic acid" refers to methacrylic acid or acrylic acid.

[0015] If the total content exceeds the upper limit, it is difficult to suppress an increase in melt viscosity during molding of the ionomer resin granules, which tends to reduce the molding processability of the ionomer resin granules. Furthermore, if the total content is less than the lower limit, the transparency of the resulting ionomer resin granules, particularly the transparency when slowly cooled to promote crystallization of the ionomer resin (hereinafter also referred to as transparency upon slow cooling), tends to decrease. The total content is 6 mol% or more, preferably 6.5 mol% or more, more preferably 7.0 mol% or more, and even more preferably 7.5 mol% or more, from the viewpoint of easily improving the transparency (particularly the transparency upon slow cooling) and adhesion to substrates such as glass of the ionomer resin granules. Furthermore, from the viewpoint of easily improving the molding processability, it is 10 mol% or less, preferably 9.9 mol% or less, and more preferably 9.5 mol% or less.

[0016] The total content of the units (A) and the units (B) can be adjusted by the method for producing a crude ionomer resin described below. More specifically, the total content can be adjusted by the reactivity (conversion rate) of each reaction for converting (meth)acrylic acid ester units in an ethylene-(meth)acrylic acid ester copolymer, which is a raw material for the crude ionomer resin, into (meth)acrylic acid units (A) and (meth)acrylic acid neutralized product units (B) through the saponification reaction and the demetallation reaction.

[0017] Examples of the monomer constituting the (meth)acrylic acid unit (A) include acrylic acid and methacrylic acid, and from the viewpoints of heat resistance and adhesion to substrates, methacrylic acid is preferred. These (meth)acrylic acid units may be used alone or in combination.

[0018] The content of the (meth)acrylic acid unit (A) in the crude ionomer resin is not particularly limited, as long as the total content of the unit (A) and the unit (B) is within the range of 6 to 10 mol % based on all monomer units constituting the crude ionomer resin. In one embodiment of the present invention, the content of the (meth)acrylic acid unit (A) in the crude ionomer resin is preferably 4.5 mol % or more, more preferably 5.0 mol % or more, even more preferably 5.5 mol % or more, particularly preferably 5.8 mol % or more, based on all monomer units constituting the crude ionomer resin, and is preferably 9.0 mol % or less, more preferably 8.5 mol % or less, even more preferably 8.0 mol % or less, particularly preferably 7.5 mol % or less. When the content of the unit (A) is equal to or greater than the above-mentioned lower limit, the transparency of the ionomer resin granules and their adhesion to substrates are likely to be improved. When the content is equal to or less than the above-mentioned upper limit, the moldability is likely to be improved.

[0019] The (meth)acrylic acid neutralization unit (B) is preferably a neutralization unit of the (meth)acrylic acid unit (A). The (meth)acrylic acid neutralization product is a product in which the hydrogen ions of (meth)acrylic acid are replaced with metal ions. Examples of the metal ions include ions of monovalent metals such as lithium, sodium, and potassium, and ions of polyvalent metals such as magnesium, calcium, zinc, aluminum, and titanium. These metal ions may be used alone or in combination of two or more. For example, a combination of one or more monovalent metal ions and one or more divalent metal ions may be used.

[0020] The content of the (meth)acrylic acid neutralization unit (B) in the crude ionomer resin is not particularly limited, as long as the total content of the unit (A) and the unit (B) is within the range of 6 to 10 mol % based on all monomer units constituting the crude ionomer resin. In one embodiment of the present invention, the content of the (meth)acrylic acid neutralization unit (B) is preferably 0.65 mol % or more, more preferably 1.0 mol % or more, even more preferably 1.5 mol % or more, particularly preferably 1.7 mol % or more, based on all monomer units constituting the crude ionomer resin, and is preferably 3.0 mol % or less, more preferably 2.7 mol % or less, even more preferably 2.6 mol % or less, particularly preferably 2.5 mol % or less. When the content of the unit (B) is equal to or greater than the above-mentioned lower limit, transparency and elastic modulus are easily improved, and when it is equal to or less than the above-mentioned upper limit, an increase in melt viscosity during molding is easily suppressed.

[0021] When an ionomer resin is produced using an ethylene-(meth)acrylic acid ester copolymer as a raw material by a method including a saponification reaction step and a demetallation reaction step of the copolymer, the contents of the units (A) and the units (B) can be adjusted by the reactivity in each reaction for converting the (meth)acrylic acid ester units in the ethylene-(meth)acrylic acid ester copolymer into (meth)acrylic acid units (A) and (meth)acrylic acid neutralization product units (B) by the saponification reaction and the demetallation reaction.

[0022] The content of ethylene units (C) is preferably 90 mol% or more, more preferably 90.5 mol% or more, and even more preferably 91 mol% or more, based on the total monomer units constituting the crude ionomer resin, from the viewpoints of easily increasing the impact resistance of the ionomer resin granules and easily increasing the melting point and maintaining heat resistance, and from the viewpoints of easily increasing the transparency of the ionomer resin granules (particularly the transparency during slow cooling), it is preferably 94 mol% or less, more preferably 93 mol% or less, and even more preferably 92.5% or less. When the content of ethylene units (C) is equal to or more than the above lower limit, mechanical properties and moldability are easily improved, and when it is equal to or less than the above upper limit, transparency is easily improved.

[0023] In one embodiment of the present invention, the crude ionomer resin preferably further contains (meth)acrylic acid ester units (D) in addition to the (meth)acrylic acid units (A), (meth)acrylic acid neutralized unit (B), and ethylene unit (C), from the viewpoint of easily obtaining higher transparency.

[0024] When the crude ionomer resin contains (meth)acrylic acid ester units (D), the total content of the units (A), (B), and (D) is preferably 6 to 10 mol % based on all monomer units constituting the crude ionomer resin, from the viewpoint of easily improving transparency (particularly transparency upon slow cooling). When the crude ionomer resin contains (meth)acrylic acid ester units (D), when the total content of the units (A), (B), and (D) is equal to or less than the above upper limit, an increase in melt viscosity during molding of the ionomer resin granules is easily suppressed, thereby easily improving the molding processability of the ionomer resin granules. On the other hand, when the total content is equal to or greater than the lower limit, the transparency of the ionomer resin granules, particularly transparency upon slow cooling, is easily improved.

[0025] When the crude ionomer resin contains the (meth)acrylic acid ester unit (D), the total content of the unit (A), the unit (B), and the unit (D) is 6 mol % or more, preferably 6.5 mol % or more, more preferably 7.0 mol % or more, and even more preferably 7.5 mol % or more, from the viewpoint of easily improving transparency (particularly transparency upon slow cooling) and adhesion to a substrate, and is 10 mol % or less, preferably 9.9 mol % or less, and more preferably 9.5 mol % or less, from the viewpoint of moldability.

[0026] The total content of the units (A), (B), and (D) can be adjusted by the raw materials of the crude ionomer resin, specifically, by the amount of (meth)acrylic acid ester modification of the ethylene-(meth)acrylic acid ester copolymer, which is the raw material of the crude ionomer resin.

[0027] Examples of monomers constituting the (meth)acrylic acid ester unit (D) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, pentadecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, glycidyl (meth)acrylate, and allyl (meth)acrylate. Of these, from the viewpoint of transparency or heat resistance, preferred monomers are methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, and t-butyl (meth)acrylate, more preferred monomers are methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate, even more preferred monomers are methyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate, and particularly preferred monomer is methyl (meth)acrylate. These (meth)acrylic acid esters may be used alone or in combination of two or more.

[0028] When the crude ionomer resin contains (meth)acrylic acid ester units (D), the content of the (meth)acrylic acid ester units (D) in the crude ionomer resin is not particularly limited. In one embodiment of the present invention, the content of the (meth)acrylic acid ester units (D) in the crude ionomer resin, based on all monomer units constituting the crude ionomer resin, is preferably more than 0 mol%, more preferably 0.01 mol% or more, even more preferably 0.05 mol% or more, particularly preferably 0.08 mol% or more, and is preferably 1.0 mol% or less, more preferably 0.7 mol% or less, and even more preferably 0.5 mol% or less. When the content of units (D) is at least the above-mentioned lower limit and at most the above-mentioned upper limit, the transparency of the ionomer resin granules is likely to be improved.

[0029] When the crude ionomer resin contains (meth)acrylic acid ester units (D), the content of the units (D) can be adjusted by the reactivity of the saponification reaction of converting the (meth)acrylic acid ester units (D) in the ethylene-(meth)acrylic acid ester copolymer into (meth)acrylic acid units (A) when the ionomer resin is produced using an ethylene-(meth)acrylic acid ester copolymer as a raw material by a method including a saponification reaction step and a demetallation reaction step of the copolymer.

[0030] In one embodiment of the present invention, the crude ionomer resin may contain other monomer units in addition to the (meth)acrylic acid units (A), (meth)acrylic acid neutralization units (B), and ethylene units (C), as well as the (meth)acrylic acid ester units (D) optionally contained. Examples of such other monomer units include carboxylic acid units (A1) other than (meth)acrylic acid units and carboxylic acid neutralization units (B1) other than (meth)acrylic acid neutralization units. Examples of monomers constituting the carboxylic acid units (A1) include itaconic acid, maleic anhydride, monomethyl maleate, and monoethyl maleate, with monomethyl maleate and monoethyl maleate being preferred. Examples of monomers constituting the carboxylic acid neutralization units (B1) include neutralized units of the carboxylic acid units (A1). Note that carboxylic acid neutralization products are products in which the hydrogen ions of carboxylic acids are replaced with metal ions. Examples of the metal ions include those similar to those in the (meth)acrylic acid neutralization unit (B), and the metal ions may be of one type alone or in combination of two or more types. These other monomer units may be of one type alone or in combination of two or more types.

[0031] When the crude ionomer resin contains the other monomer units, the total content of the other monomer units, for example, the total content of (A1) and (B1), may be appropriately selected within a range that does not impair the effects of the present invention. For example, based on all monomer units constituting the crude ionomer resin, the total content of the other monomer units is preferably 5 mol % or less, more preferably 3 mol % or less, and even more preferably 1 mol % or less, and is also preferably 0.01 mol % or more, and more preferably 0.1 mol % or more.

[0032] The contents of the (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), and ethylene units (C), as well as the (meth)acrylic acid ester units (D) and other monomer units (e.g., units (A1) and (B1)) contained in the crude ionomer resin of the present invention can be determined by first identifying the monomer units in the crude ionomer resin by pyrolysis gas chromatography, and then using nuclear magnetic resonance spectroscopy (NMR) and elemental analysis. Furthermore, since the contents of the monomer units in the ionomer resin granules obtained by the production method of the present invention correspond to the contents of the monomer units in the crude ionomer resin, the contents of the monomer units in the crude ionomer resin may be determined by analyzing the obtained ionomer resin granules instead of the crude ionomer resin. More specifically, the contents can be determined by the methods described in the Examples. Furthermore, the contents can also be determined by a method combining the above analyses with IR and / or Raman analysis. Prior to these analyses, it is preferable to remove components other than the crude ionomer resin or the obtained ionomer resin granules by reprecipitation or Soxhlet extraction.

[0033] (Method for Producing Crude Ionomer Resin) The method for producing the crude ionomer resin is not particularly limited, and examples thereof include the EMMA saponification method, specifically a method using an ethylene-(meth)acrylic acid ester copolymer (X) as a raw material and converting all or a portion of the (meth)acrylic acid ester units in the copolymer into (meth)acrylic acid units and (meth)acrylic acid neutralized product units. Examples of the method for converting all or a portion of the (meth)acrylic acid ester units into (meth)acrylic acid units and (meth)acrylic acid neutralized product units include a method (hereinafter also referred to as method (1)) in which the ethylene-(meth)acrylic acid ester copolymer (X) is saponified with an alkali to convert all or a portion of the (meth)acrylic acid ester units into (meth)acrylic acid neutralized product units, thereby obtaining an ethylene-(meth)acrylic acid neutralized product copolymer or an ethylene-(meth)acrylic acid ester-(meth)acrylic acid neutralized product copolymer, and then demetallizing a portion of the (meth)acrylic acid neutralized product units in the obtained copolymer with an acid to convert them into (meth)acrylic acid units. An example of a method other than the method (1) is a method in which all of the (meth)acrylic acid neutralization units in an ethylene-(meth)acrylic acid neutralization copolymer or an ethylene-(meth)acrylic acid ester-(meth)acrylic acid neutralization copolymer obtained by the saponification in the method (1) are demetalized with an acid to convert them into (meth)acrylic acid units, thereby obtaining an ethylene-(meth)acrylic acid copolymer or an ethylene-(meth)acrylic acid ester-(meth)acrylic acid copolymer, and then neutralizing a portion of the (meth)acrylic acid units in the obtained copolymer with a metal ion (hereinafter also referred to as method (2)). Of the methods (1) and (2), the method (1) is preferred for producing a crude ionomer resin, from the viewpoint of reducing the number of reactions and easily improving the production efficiency of the ionomer resin.

[0034] Examples of monomers constituting the (meth)acrylic acid ester units of the ethylene-(meth)acrylic acid ester copolymer (X) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, pentadecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, glycidyl (meth)acrylate, and allyl (meth)acrylate. Of these, preferred monomers are methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, and t-butyl (meth)acrylate, more preferred monomers are methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate, still more preferred monomers are methyl (meth)acrylate, n-butyl (meth)acrylate, and isobutyl (meth)acrylate, and particularly preferred is methyl (meth)acrylate. These (meth)acrylic acid esters may be used alone or in combination of two or more.

[0035] Specific examples of the ethylene-(meth)acrylic acid ester copolymer (X) include ethylene-methyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-ethyl methacrylate copolymer, ethylene-n-propyl acrylate copolymer, ethylene-n-propyl methacrylate copolymer, ethylene-isopropyl acrylate copolymer, ethylene-isopropyl methacrylate copolymer, ethylene-n-butyl acrylate copolymer, ethylene-n-butyl methacrylate copolymer, ethylene-sec-butyl acrylate copolymer, ethylene-sec-butyl methacrylate copolymer, etc. As these copolymers, commercially available products may be used, or those synthesized by the high-temperature, high-pressure radical polymerization method described in US 2013 / 0274424, JP 2006-233059, or JP 2007-84743 may also be used. Examples of commercially available products include "Aclift" (registered trademark) WD301F and WK307 manufactured by Sumitomo Chemical Co., Ltd., "Rexpearl" (registered trademark) A4250 manufactured by Japan Polyethylene Corporation, and NUC-6070 manufactured by NUC Corporation.

[0036] The content of (meth)acrylic acid ester units in the ethylene-(meth)acrylic acid ester copolymer (X) is preferably 6 mol% or more, more preferably 6.5 mol% or more, even more preferably 7 mol% or more, and particularly preferably 7.5 mol% or more, and is preferably 10 mol% or less, more preferably 9.9 mol% or less, and even more preferably 9.5 mol% or less. The total content of (meth)acrylic acid units (A) and (meth)acrylic acid neutralized units (B), as well as (meth)acrylic acid ester units (D), if present, in the resulting crude ionomer resin and ionomer resin granules can be adjusted by the content of (meth)acrylic acid ester units in the copolymer (X). Therefore, when the content of (meth)acrylic acid ester units in the copolymer (X) is at least the above-mentioned lower limit, the transparency of the resulting ionomer resin granules, particularly the transparency during slow cooling, is likely to be improved. When the content is at most the above-mentioned upper limit, the molding processability of the resulting ionomer resin is likely to be improved. The content can be adjusted by the copolymerization ratio of ethylene and (meth)acrylic acid ester. The above content can be determined by pyrolysis gas chromatography, nuclear magnetic resonance spectroscopy (NMR), and elemental analysis, similarly to the contents of the (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), and ethylene units (C), as well as the (meth)acrylic acid ester units (D) and other monomer units (e.g., units (A1) and units (B1)) contained in the crude ionomer resin.

[0037] In one embodiment of the present invention, the melt flow rate (MFR) of the ethylene-(meth)acrylic acid ester copolymer (X), measured in accordance with JIS K7210-1:2014 under conditions of 190°C and 2.16 kg, is preferably 1 g / 10 min or more, more preferably 5 g / 10 min or more, even more preferably 10 g / 10 min or more, even more preferably 50 g / 10 min or more, and particularly preferably 100 g / 10 min or more, and is preferably 400 g / 10 min or less, more preferably 350 g / 10 min or less, even more preferably 300 g / 10 min or less, and even more preferably 250 g / 10 min or less. When the MFR of the ethylene-(meth)acrylic acid ester copolymer (X) is at least the above-mentioned lower limit and is at most the above-mentioned upper limit, the molding processability of the resulting ionomer resin granules is likely to be improved. Furthermore, the strength of the resulting ionomer resin granules is likely to be increased, and the handleability is likely to be improved. The MFR of the ethylene-(meth)acrylic acid ester copolymer (X) can be adjusted by the degree of polymerization and the content of the (meth)acrylic acid ester unit. The MFR can be measured, for example, by the method described in the Examples.

[0038] From the viewpoint of easily improving the moldability and strength of the resulting ionomer resin granules, the weight average molecular weight of the ethylene-(meth)acrylic acid ester copolymer (X) is preferably 15,000 g / mol or more, more preferably 20,000 g / mol or more, even more preferably 30,000 g / mol or more, and preferably 200,000 g / mol or less, more preferably 100,000 g / mol or less. From the same viewpoint, the number average molecular weight of the ethylene-(meth)acrylic acid ester copolymer (X) is preferably 5,000 g / mol or more, more preferably 10,000 g / mol or more, even more preferably 15,000 g / mol or more, and preferably 100,000 g / mol or less, more preferably 50,000 g / mol or less. The weight average molecular weight and number average molecular weight can be adjusted by the amount of polymerization initiator and / or chain transfer agent used during polymerization. The molecular weights (weight average molecular weight and number average molecular weight) of these ethylene-(meth)acrylic acid ester copolymers (X) were measured using a column (TSKgel GMH ＨＲMeasurements can be performed in polystyrene equivalents using three -H(20)HT columns in series and 1,2,4-trichlorobenzene as the solvent at a column temperature of 140°C.

[0039] The degree of branching per 1000 carbon atoms of the ethylene-(meth)acrylic acid ester copolymer (X) is not particularly limited, and is preferably 5 to 30, more preferably 6 to 20. The degree of branching can be adjusted by the polymerization temperature when polymerizing the copolymer (X). The degree of branching per 1000 carbon atoms can be adjusted by dissolving the ethylene-(meth)acrylic acid ester copolymer (X) in deuterated orthodichlorobenzene, １３ It can be measured by the inverse gate decoupling method of C-NMR.

[0040] Examples of the alkali used in the saponification reaction in the above methods (1) and (2) include strong bases such as sodium hydroxide, potassium hydroxide, and calcium hydroxide, and sodium hydroxide and potassium hydroxide are preferred from the viewpoints of solubility in the solvent used in the saponification reaction and economy.

[0041] Examples of solvents used in the saponification reaction include ethers such as tetrahydrofuran and dioxane; halogen-containing solvents such as chloroform and dichlorobenzene; ketones having 6 or more carbon atoms such as methyl butyl ketone; mixed solvents of hydrocarbon compounds and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol; aromatic compounds such as benzene, toluene, xylene, and ethylbenzene; and mixed solvents of aromatic compounds and alcohols. These solvents may be used alone or in combination of two or more. Among these, from the viewpoint of the solubility of the resin before and after the saponification reaction, preferred solvents are mixed solvents of hydrocarbon compounds and alcohols, and mixed solvents of aromatic compounds and alcohols, and more preferred solvents are mixed solvents of aromatic compounds such as toluene and alcohols such as methanol. The ratio of the hydrocarbon compound or aromatic compound to the alcohols in the mixed solvent may be appropriately selected depending on the type of each solvent used. For example, the mass ratio of the hydrocarbon compound or aromatic compound to the alcohols (hydrocarbon compound or aromatic compound / alcohols) may be 50 / 50 to 90 / 10.

[0042] The temperature at which the saponification reaction is carried out is, from the viewpoints of the reactivity and the solubility of the ethylene-(meth)acrylic acid ester copolymer (X), preferably 50° C. or higher, more preferably 60° C. or higher, even more preferably 70° C. or higher, and particularly preferably 80° C. or higher. The upper limit of the temperature is not particularly limited as long as it is lower than the temperature at which the ethylene-(meth)acrylic acid ester copolymer (X) decomposes, and is, for example, 300° C. or lower.

[0043] The saponification reaction may be carried out in air or in an inert gas such as nitrogen gas or argon gas, and may be carried out under normal pressure, elevated pressure, or reduced pressure, preferably elevated pressure.

[0044] Examples of the acid used for demetallation in the above methods (1) and (2) include strong acids such as hydrochloric acid, nitric acid, sulfuric acid, toluenesulfonic acid, etc. From the viewpoint of ease of removal of salts after demetallation, inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, etc. The solvent used for the demetallation can be the same as the solvent used for the above saponification reaction.

[0045] The temperature at which the demetallization is carried out is preferably 20°C or higher, more preferably 30°C or higher, and even more preferably 40°C or higher, from the viewpoint of resin solubility and ease of reducing the viscosity of the reaction solution, and is preferably 100°C or lower, more preferably 80°C or lower, even more preferably 70°C or lower, and even more preferably 60°C or lower.

[0046] The demetallation may be carried out in air or in an inert gas such as nitrogen gas or argon gas, similarly to the saponification reaction, and may be carried out under normal pressure, elevated pressure, or reduced pressure, preferably elevated pressure.

[0047] In the above method (2), the neutralizing agent used when neutralizing a portion of the (meth)acrylic acid units to convert them into (meth)acrylic acid neutralized units is not particularly limited as long as it is an ionic compound containing a metal ion. Examples of the metal ion include alkali metal ions such as lithium, potassium, and sodium, alkaline earth metal ions such as magnesium and calcium, transition metal ions such as zinc, nickel, iron, and titanium, and aluminum ions. For example, when the metal ion is sodium ion, examples of the neutralizing agent include sodium hydroxide, sodium acetate, and sodium bicarbonate. In addition, polymers such as ionomer resins containing sodium (meth)acrylate units can also be used as the neutralizing agent.

[0048] In one embodiment of the present invention, the degree of saponification in the crude ionomer resin obtained by the EMMA saponification method, i.e., the ratio of the total of the (meth)acrylic acid units (A) and the (meth)acrylic acid neutralized units (B) to the total of the (meth)acrylic acid units (A), the (meth)acrylic acid neutralized units (B), and the (meth)acrylic acid ester units (D), may be preferably 85 to 100%, more preferably 87 to 99.5%, and even more preferably 90 to 99%, from the viewpoint of easily improving adhesion to glass. Also, in one embodiment of the present invention, the degree of neutralization in the crude ionomer resin obtained by the EMMA saponification method, i.e., the ratio of the (meth)acrylic acid neutralized units (B) to the total of the (meth)acrylic acid units (A) and the (meth)acrylic acid neutralized units (B), is preferably 0 to 55%, more preferably 10 to 40%, and even more preferably 15 to 30%, from the viewpoint of easily forming into a resin sheet and easily increasing the transparency of the resulting resin sheet during annealing.

[0049] (Solvent) The solvent used in step (I) is not particularly limited as long as it is capable of dissolving the crude ionomer resin, and examples thereof include ethers such as tetrahydrofuran and dioxane; halogen-containing solvents such as chloroform and dichlorobenzene; ketones having 6 or more carbon atoms such as methyl butyl ketone; nitrogen-containing compounds such as pyridine, N-methyl-2-pyrrolidone and dimethylformamide; hydrocarbon compounds such as n-heptane, n-hexane and cyclohexane; alcohols such as methanol, ethanol, 1-propanol, 2-propanol and 1-butanol; aromatic compounds such as benzene, toluene, xylene and ethylbenzene; and mixed solvents thereof. Of these, a mixed solvent of an aromatic compound such as toluene and an alcohol such as methanol is preferred from the viewpoint of the solubility of the crude ionomer resin. The ratio of the aromatic compound to the alcohol in the mixed solvent may be appropriately selected depending on the type of each solvent used. For example, the mass ratio of the aromatic compound to the alcohol (aromatic compound / alcohol) may be 50 / 50 to 90 / 10, preferably 60 / 40 to 85 / 15, and more preferably 65 / 35 to 80 / 20.

[0050] These solvents used in step (I) may contain water to the extent that the crude ionomer resin can be dissolved in the solvent. In one embodiment of the present invention, from the viewpoint of the solubility of the crude ionomer resin, the water content is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably less than 15% by mass, and particularly preferably 14% by mass or less, relative to the total mass of the solvent, and is preferably 0% by mass or more, more preferably 0.1% by mass or more, and even more preferably 1% by mass or more.

[0051] (Mixture containing crude ionomer resin and solvent) The mixture containing crude ionomer resin and solvent in step (I) (hereinafter also referred to simply as "mixture" or "crude ionomer resin mixture") can be prepared by mixing the crude ionomer resin with a solvent. In one embodiment of the present invention, a reaction solution of a crude ionomer resin obtained by producing a crude ionomer resin by the above-mentioned method (1) or (2), or a mixture obtained by further adding a solvent to the reaction solution, may be used as the mixture containing crude ionomer resin and solvent.

[0052] In one embodiment of the present invention, the concentration of the crude ionomer resin in the crude ionomer resin mixture is preferably less than 19% by mass, more preferably 18% by mass or less, even more preferably 16% by mass or less, even more preferably 14% by mass or less, and particularly preferably 12% by mass or less. The lower the concentration of the crude ionomer resin in the mixture, the easier it is to increase the porosity of the resulting granules. Therefore, when the concentration is less than or equal to the above-mentioned upper limit, it is easy to adjust the porosity of the resulting granules to 60% or more, thereby improving salt removal and facilitating the production of ionomer resin granules with excellent transparency. Furthermore, the concentration of the crude ionomer resin in the mixture is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and particularly preferably 8% by mass or more. When the concentration is equal to or greater than the above-mentioned lower limit, it is easy to obtain ionomer resin granules with high strength and excellent handleability.

[0053] (Extrusion and Cooling) The method for extruding the crude ionomer resin mixture and cooling the extruded mixture to solidify the crude ionomer resin in the mixture is not particularly limited. When the extruded mixture is cooled to solidify the crude ionomer resin in the mixture, the solvent portion of the solidified crude ionomer resin becomes pores, and therefore a porous solid can be obtained.

[0054] In one embodiment of the present invention, the temperature of the mixture when extruding the mixture is preferably 68°C or lower, more preferably 65°C or lower, even more preferably 63°C or lower, still more preferably 60°C or lower, and particularly preferably 55°C or lower, from the viewpoints of easily obtaining porous granules having a porosity of 60% or higher in step (I) and easily preventing the obtained porous granules from agglomerating and improving handleability. Furthermore, from the viewpoint of easily improving the fluidity of the mixture, the temperature of the mixture is preferably 30°C or higher, more preferably 35°C or higher, even more preferably 38°C or higher, and particularly preferably 40°C or higher. The temperature may be appropriately selected depending on the concentration of the crude ionomer resin in the mixture; when the concentration of the crude ionomer resin is relatively low, the granules are less likely to aggregate or agglomerate, and the temperature of the mixture can be relatively low.

[0055] The method for cooling the extruded mixture is not particularly limited, and although the extruded mixture may be cooled with cold air, it is preferable to cool the extruded mixture by contacting it with a poor solvent. Cooling the extruded mixture by contacting it with a poor solvent increases the cooling rate, suppresses bleeding of the solvent from the mixture, and makes it easy to adjust the porosity of the granules to 60% or more. Also, it suppresses the progression of phase separation between the crude ionomer resin and the solvent, making it easy to prevent the median diameter of the pores in the granules from becoming excessively large, which tends to improve the transparency and handleability of the resulting ionomer resin granules.

[0056] The poor solvent for cooling the mixture is not particularly limited as long as it is a solvent that can solidify the crude ionomer resin in the mixture, but water, alcohol, or a mixed solvent of these is preferred from the viewpoint of facilitating the dissolution and removal of salts in the crude ionomer resin mixture. Examples of alcohol include methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol, with methanol and ethanol being preferred, and methanol being more preferred. The alcohol may be used alone or in combination of two or more. Of these poor solvents, water is preferred.

[0057] The temperature of the poor solvent is not particularly limited as long as it can cool the extruded mixture, i.e., as long as it is lower than the temperature of the extruded mixture. In one embodiment of the present invention, the temperature of the poor solvent is preferably 60°C or lower, more preferably 50°C or lower, even more preferably 40°C or lower, and particularly preferably 30°C or lower, from the viewpoints of facilitating solidification of the crude ionomer resin in the mixture, increasing the cooling rate, and facilitating adjustment of the porosity to 60% or higher. The temperature may also be 0°C or higher.

[0058] In one embodiment of the present invention, the temperature difference between the mixture temperature and the poor solvent temperature during extrusion is preferably 10°C or more, more preferably 20°C or more, even more preferably 30°C or more, and preferably 60°C or less, from the viewpoint of increasing the cooling rate and making it easy to adjust the porosity to 60% or more.

[0059] The method for contacting the extruded mixture with the poor solvent is not particularly limited, and examples thereof include immersing the extruded mixture in the poor solvent or pouring the poor solvent onto the extruded mixture.

[0060] The method for obtaining porous granules from a crude ionomer resin mixture is not particularly limited, and examples thereof include a method of extruding the crude ionomer resin mixture into a poor solvent in the form of strands and cutting the resulting strands (strand method), a method of extruding the crude ionomer resin mixture into a poor solvent and cutting the mixture immediately after extrusion (underwater hot-cut method), a method of extruding the crude ionomer resin mixture, cutting the mixture immediately after extrusion, and bringing the resulting cut pieces into contact with a poor solvent (hot-cut method), etc. The cutting may be performed using a strand cutter or the like.

[0061] (Porous granules) The porous granules obtained in step (I) have a porosity of 60% or more. When the porosity of the porous granules is 60% or more, the surface area is increased, making it easier to remove salt from the granules, and therefore, an ionomer resin granule with excellent transparency and handleability can be obtained.

[0062] In one embodiment of the present invention, the porosity of the granules obtained in step (I) is preferably 62% or more, more preferably 64% or more, even more preferably 68% or more, and particularly preferably 70% or more. When the porosity is equal to or greater than the above-mentioned lower limit, salt removal can be improved, making it easier to obtain ionomer resin granules with excellent transparency. Furthermore, the porosity is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less. When the porosity is equal to or less than the above-mentioned upper limit, it is easier to obtain ionomer resin granules with high strength and excellent handleability.

[0063] The porosity of the granules obtained in step (I) can be adjusted by the concentration of crude ionomer resin in the crude ionomer resin mixture, the temperature during extrusion of the crude ionomer resin mixture, the extrusion rate, the cooling rate, the size of the granules, etc. For example, increasing the concentration of crude ionomer resin in the crude ionomer resin mixture, slowing the cooling rate, or increasing the size of the granules tends to decrease the porosity, while decreasing the concentration of the crude ionomer resin mixture, increasing the cooling rate, or decreasing the size of the granules tends to increase the porosity.

[0064] In one embodiment of the present invention, the median pore diameter of the granules obtained in step (I) is preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.3 μm or more, and particularly preferably 0.5 μm or more, from the viewpoint of improving salt removal properties and facilitating the production of ionomer resin granules having excellent transparency. Furthermore, the median pore diameter is preferably 1.2 μm or less, more preferably 1.0 μm or less, even more preferably 0.9 μm or less, and particularly preferably 0.8 μm or less, from the viewpoint of facilitating the production of ionomer resin granules having high strength and excellent handleability.

[0065] The porosity and median pore diameter can be measured by mercury intrusion porosimetry using a pore size distribution analyzer, for example, by the method described in the Examples. Note that the porosity and median pore diameter of the granules obtained in step (I) are hardly or not changed by the washing step described below, etc., and therefore the porosity and median pore diameter of the obtained ionomer resin granules can also be used as the porosity and median pore diameter of the granules obtained in step (I).

[0066] In one embodiment of the present invention, the granules obtained in step (I) are preferably pellets in the shape of spheres, cylinders, elliptical cylinders, polygonal pillars, or rugby balls, and more preferably cylindrical, elliptical cylinders, or polygonal pillars. In one embodiment of the present invention, the pellet size is preferably 1 mm or more, more preferably 1.5 mm or more, and even more preferably 2 mm or more, from the viewpoint of easily obtaining ionomer resin granules with excellent handleability. Furthermore, the pellet size is preferably 8 mm or less, more preferably 6 mm or less, and even more preferably 5 mm or less, from the viewpoint of easily adjusting the porosity to 60% or more and easily obtaining ionomer resin granules with excellent transparency.

[0067] In the present invention, when the pellets are cylindrical, elliptical, or polygonal, the pellet size per pellet is the average value ((Lx + Ly + Lz) / 3) of the X-axis length (Lx), Y-axis length (Ly), and Z-axis length (Lz) of the pellet, and the pellet size is preferably the arithmetic mean value of the average X-axis, Y-axis, and Z-axis lengths of at least 10 pellets. Here, the X-axis length (Lx) of the pellet is the height of the pellet, the Y-axis length (Ly) is the diameter or the longest diagonal length of the plane perpendicular to the X-axis (the base of the pellet), and the Z-axis length (Lz) is the diameter or the shortest diagonal length of the pellet's base. Note that when the base is triangular, the Y-axis length (Ly) is the longest side of the base, and the Z-axis length (Lz) is the shortest side of the base. Therefore, for example, in the case of elliptical cylindrical pellets, the pellet size per pellet is the average value of the height (Lx), major axis diameter (Ly), and minor axis diameter (Lz) of the elliptical cylinder ((height + major axis diameter + minor axis diameter) / 3). A conceptual diagram of the X-axis length (Lx), Y-axis length (Ly), and Z-axis length (Lz) of a pellet is shown in FIG. 1. The right-hand diagram in FIG. 1 is a plan view of the pellet shown in the left-hand diagram in FIG. 1 as viewed from the X-axis direction. The pellet size can be calculated by measuring the X-axis length (Lx), Y-axis length (Ly), and Z-axis length (Lz) of each pellet using a micrometer or the like, and can be determined, for example, by the method described in the Examples. Furthermore, in the present invention, when the pellets are spherical, the pellet size per pellet is the diameter of the pellet, and the pellet size is preferably the average value of the diameters of 10 or more pellets. In the present invention, when the pellets are rugby ball-shaped, the pellet size per pellet is the average value of the major and minor axes of the pellet ((major axis + minor axis) / 2), and the pellet size is preferably the arithmetic mean value of the average major and minor axes of 10 or more pellets. In one embodiment of the present invention, the pellet size can be adjusted by the diameter of the die during extrusion, the length of the extruded mixture in the extrusion direction during cutting, etc.

[0068] <Step (II)> In one embodiment of the present invention, it is preferable that the method of the present invention further comprises a step of washing the porous granules obtained in step (I) with a washing liquid (hereinafter also referred to as "step (II)"). By washing the granules having a porosity of 60% or more obtained in step (I) with a washing liquid in step (II), salt in the granules is easily removed, making it easy to reduce the salt content in the resulting ionomer resin granules and to obtain ionomer resin granules that have excellent transparency, particularly transparency when water is absorbed.

[0069] The cleaning liquid is not particularly limited as long as it is a solvent that does not dissolve the ionomer resin granules and can dissolve the salt. Preferred examples of cleaning liquids include alcohols such as methanol, ethanol, 1-propanol, and 2-isopropanol; water; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; and ethers such as dimethyl ether, diethyl ether, and tetrahydrofuran. These may be used alone or in combination of two or more.

[0070] Among these cleaning solutions, alcohols, water, and mixtures thereof are preferred, and a mixture of water and alcohols is more preferred, from the viewpoint of high salt solubility and easy removal of salt contained in the porous granules obtained in step (I). A mixture of water and alcohols as the cleaning solution is likely to increase salt solubility and make the specific gravity of the cleaning solution lower than that of the granules, thereby increasing the contact area between the cleaning solution and the granules and improving salt removal. Furthermore, impurities such as organic compounds contained in the granules are easily removed, and the ionomer resin granules obtained after washing are easily dried. Preferred alcohols are methanol and ethanol, more preferably methanol, because they are easy to dry and have high compatibility with water. The ratio of water to alcohol (water / alcohols (mass%)) in the mixture of water and alcohols is preferably 20 / 80 to 80 / 20, more preferably 30 / 70 to 70 / 30.

[0071] The method for washing the granules obtained in step (I) with a washing liquid is not particularly limited, and examples thereof include a method in which the granules obtained in step (I) are mixed with a washing liquid and then dewatered. More specifically, examples include a washing method in which the granules are mixed with a washing liquid, and the granules are filtered out of the washing liquid (hereinafter also referred to as washing step (a)), and then the filtered granules are mixed with new washing liquid and then filtered out of the washing liquid (hereinafter also referred to as washing step (b)). From the viewpoint of reducing the salt content in the granules and making it easier to obtain ionomer resin granules that are excellent in transparency, particularly transparency upon water absorption, and from the viewpoint of making it easier to improve the efficiency of the separation and purification step of the ionomer resin granules, in the case of a batch process, the granules are preferably washed, for example, by performing one washing step (a) followed by one to ten washing steps (b), and the number of times that one washing step (a) followed by one washing step (b) is more preferably one to six, and even more preferably one to four.

[0072] The amount of the cleaning solution used per washing step may be appropriately selected depending on the amount of granular material to be washed. For example, the amount of the cleaning solution used per washing step is preferably 100 to 2,000 parts by mass, more preferably 200 to 1,000 parts by mass, and even more preferably 300 to 700 parts by mass, per 100 parts by mass of the granular material on a dry basis.

[0073] The ionomer resin granules washed in step (II) may be dried, if necessary, at a temperature preferably equal to or lower than the melting point of the ionomer resin granules, more preferably equal to or lower than 80°C.

[0074] <Ionomer Resin Granules> The method of the present invention includes step (I) and, optionally, step (II), which can improve salt removal properties. As a result, the ionomer resin granules, i.e., the ionomer resin granules obtained by the method of the present invention, are excellent in transparency and handleability.

[0075] In one embodiment of the present invention, the crude ionomer resin contains, for example, 100,000 to 500,000 mg / kg of salts formed by the neutralization reaction between alkali and acid during the process of producing the crude ionomer resin. However, the ionomer resin granules obtained by the method of the present invention have excellent transparency because the salts formed during the process of producing the crude ionomer resin are sufficiently reduced. The salts formed during the process of producing the crude ionomer resin are salts formed from the strong bases described above as the alkalis used in the saponification reaction and the strong acids described above as the acids used in the demetallization reaction. These salts may be used alone or in combination of two or more.

[0076] In one embodiment of the present invention, the salt content in the ionomer resin granules is preferably 1000 mg / kg or less, more preferably 700 mg / kg or less, even more preferably 400 mg / kg or less, even more preferably 350 mg / kg or less, particularly preferably 300 mg / kg or less, and especially preferably 250 mg / kg or less, from the viewpoint of easily improving the transparency of the ionomer resin granules, particularly transparency upon water absorption. Since the transparency of the ionomer resin granules (particularly transparency upon water absorption) tends to increase as the salt content in the ionomer resin granules decreases, the lower limit is not particularly limited and may be 0 mg / kg or more, and from the viewpoint of easily improving the thermal decomposition resistance of the ionomer resin granules, it may be preferably 1 mg / kg or more. The salt content in the ionomer resin granules can be measured using ion chromatography, for example, by the method described in the Examples.

[0077] Examples of salts of strong acids and strong bases include lithium salts, sodium salts, potassium salts, rubidium salts, and cesium salts. Preferred are alkali metal salts such as lithium salts, sodium salts, and potassium salts; and alkaline earth metal salts such as beryllium salts, magnesium salts, calcium salts, strontium salts, and barium salts. From the viewpoint of easily improving the thermal decomposition resistance of the ionomer resin granules, preferred salts are sodium salts and potassium salts. More preferred salts include salts composed of at least one cation selected from the group consisting of sodium ions, potassium ions, magnesium ions, and calcium ions, and at least one anion selected from the group consisting of halogen ions, sulfate ions, nitrate ions, and sulfonate ions. From the viewpoint of easily improving the thermal decomposition resistance of the ionomer resin granules, preferred salts are salts composed of at least one cation selected from the group consisting of sodium ions and potassium ions, and at least one anion selected from the group consisting of halogen ions, sulfate ions, and nitrate ions.

[0078] More specifically, preferred examples of salts of strong acids and strong bases include sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, sodium nitrate, potassium nitrate, magnesium nitrate, calcium nitrate, sodium p-toluenesulfonate, potassium p-toluenesulfonate, magnesium p-toluenesulfonate, and calcium p-toluenesulfonate. From the viewpoint of easily improving transparency and heat resistance, more preferred are sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, sodium nitrate, and potassium nitrate, and even more preferred are sodium chloride, sodium sulfate, and sodium nitrate.

[0079] The ionomer resin granules contain (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), and ethylene units (C), and the total content of the units (A) and (B) is 6 to 10 mol% based on all monomer units constituting the ionomer resin granules. The ionomer resin granules may contain, in addition to the units (A), (B), and ethylene units (C), other monomer units such as (meth)acrylic acid ester units (D) and / or carboxylic acid units (A1) other than (meth)acrylic acid units, or carboxylic acid neutralized units (B1) other than (meth)acrylic acid neutralized units. Examples of the units (A) and (B) in the ionomer resin granules, as well as the units (D) and other monomer units (A1) and (B1) optionally contained therein, include the same units as those described above for the units (A), (B), (D), (A1), and (B1) contained in the crude ionomer resin, and preferred forms are also the same as those for the crude ionomer resin. Furthermore, the contents of each unit in the ionomer resin granules, the total content of units (A) and (B), and, when the ionomer resin granules contain (meth)acrylic acid ester units (D), the total content of units (A), (B), and (D) are also the same as those for the crude ionomer resin, including the contents and preferred forms, described above for the crude ionomer resin.

[0080] The ionomer resin granules are preferably porous and preferably have a pore structure similar to that of the porous granules obtained in step (I). The same applies to the porosity and median pore diameter of the ionomer resin granules as those of the granules obtained in step (I). Since the porosity and median pore diameter of the ionomer resin granules change little or not at all from those of the porous granules obtained in step (I), the porosity and median pore diameter of the porous granules obtained in step (I) can also be used as the porosity and median pore diameter of the ionomer resin granules.

[0081] The ionomer resin granules are preferably pellets in the shape of spheres, cylinders, elliptical cylinders, polygonal pillars, rugby balls, etc., and more preferably cylindrical, elliptical cylinders, or polygonal pillars. The pellet size of the ionomer resin granules is similarly described for the pellet size of the granules obtained in step (I).

[0082] The degree of branching per 1000 carbon atoms of the ionomer resin granules is not particularly limited, and is preferably 5 to 30, more preferably 6 to 20. The degree of branching can be adjusted by the polymerization temperature during synthesis of the ethylene-(meth)acrylic acid ester copolymer (X), which is a raw material for the ionomer resin. The degree of branching per 1000 carbon atoms can be measured by the DDMAS method using solid-state NMR.

[0083] The melting point of the ionomer resin granules is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher from the viewpoint of heat resistance, and is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 150°C or lower from the viewpoint of facilitating the development of adhesive strength to a substrate when preparing laminated glass. The melting point can be measured in accordance with JIS K7121:2012. Specifically, the melting point can be measured using a differential scanning calorimeter (DSC) under conditions of a cooling rate of -10°C / min and a heating rate of 10°C / min, and can be determined from the pick-top temperature of the melting peak during the second heating.

[0084] The heat of fusion of the ionomer resin granules is preferably 0 J / g or more and 25 J / g or less. The heat of fusion can be measured based on JIS K7122:2012. Specifically, the heat of fusion can be measured using a differential scanning calorimeter (DSC) under conditions of a cooling rate of −10° C. / min and a heating rate of 10° C. / min, and calculated from the area of ​​the melting peak during the second heating.

[0085] The melt flow rate (MFR) of the ionomer resin granules measured in accordance with JIS K7210-1:2014 under conditions of 190°C and 2.16 kg is preferably 0.1 g / 10 min or more, more preferably 0.3 g / 10 min or more, even more preferably 0.7 g / 10 min or more, still more preferably 1.0 g / 10 min or more, particularly preferably 1.5 g / 10 min or more, and preferably 50 g / 10 min or less, more preferably 30 g / 10 min or less, particularly preferably 10 g / 10 min or less. When the MFR is at least the above lower limit and at most the above upper limit, molding processing is facilitated with suppressed deterioration due to heat, and a resin sheet with excellent penetration resistance is easily obtained.

[0086] The melting point, heat of fusion and MFR of the ionomer resin granules can be adjusted by the molecular weight of the ionomer resin and the contents of (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), ethylene units (C), and optionally (meth)acrylic acid ester units (D).

[0087] The storage modulus (E') of the ionomer resin granules at 50°C, as measured by dynamic viscoelasticity measurement, is preferably 20 MPa or more, more preferably 30 MPa or more, even more preferably 40 MPa or more, and particularly preferably 50 MPa or more, from the viewpoint of good self-supporting ability (i.e., high elastic modulus), particularly self-supporting ability in a high-temperature environment (high elastic modulus in a high-temperature environment). The upper limit of the storage modulus (E') is not particularly limited and may be 1000 MPa. The storage modulus can be adjusted by the molecular weight of the ionomer resin and the contents of the (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), and ethylene units (C), and optionally the (meth)acrylic acid ester units (D), of the ionomer resin.

[0088] The ionomer resin granules obtained by the method of the present invention have high transparency due to the reduced salt content in the ionomer resin granules. The haze of the ionomer resin granules is preferably 2.0% or less, more preferably 1.5% or less, and even more preferably 1.0% or less. Since the smaller the haze, the higher the transparency of the ionomer resin granules, the lower limit is not particularly limited and may be, for example, 0.01% or more. The haze of the ionomer resin granules is measured using a haze meter in accordance with JIS K7136:2000.

[0089] The ionomer resin granules obtained by the method of the present invention have high transparency even when the ionomer resin granules have absorbed water (during water absorption) because the salts in the ionomer resin granules have been sufficiently removed and the salt content is low. The haze of the ionomer resin granules when they have absorbed water (water absorption haze) is preferably 9.0% or less, more preferably 5.0% or less, even more preferably 4.0% or less, still more preferably 3.0% or less, and particularly preferably 2.5% or less. The smaller the water absorption haze, the higher the transparency of the ionomer resin granules when they have absorbed water, so the lower limit is not particularly limited and may be, for example, 0.01% or more. The water absorption haze can be measured using a haze meter in accordance with JIS K7136:2000, for example, by immersing a resin sheet formed from ionomer resin granules in ion-exchanged water at 23°C for 300 hours, removing it from the ion-exchanged water, and wiping off the water adhering to the surface of the resin sheet as a test piece.

[0090] According to the inventors' investigations, if the crystallinity of an ionomer resin is too high, the ionomer resin tends to whiten, and therefore the transparency (transparency upon slow cooling) of the ionomer resin when slowly cooled to promote crystallization of the resin is likely to decrease. The ionomer resin granules obtained by the present invention are resistant to crystallization and have high transparency even when slowly cooled because the total content of (meth)acrylic acid units (A) and (meth)acrylic acid neutralized units (B) in the resin is 6 mol % or more. The haze (slow cooling haze) of the ionomer resin granules obtained by the method of the present invention when crystallization of the resin is promoted by slow cooling is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, and particularly preferably 2.0% or less. Since the smaller the haze, the higher the transparency of the ionomer resin, so the lower limit is not particularly limited and may be, for example, 0.01% or more. The annealed haze can be obtained by preparing a laminated glass by placing a resin sheet formed from ionomer resin granules as an interlayer between two glass plates, heating the laminated glass to 140°C, and then annealing it from 140°C to 23°C at a rate of 0.1°C / min, and measuring the haze using a haze meter in accordance with JIS K7136:2000.

[0091] In one embodiment of the present invention, the ionomer resin granules of the present invention have a low degree of coloration, and are preferably colorless. From the viewpoint of low coloration, the yellowness index (YI) of the ionomer resin granules of the present invention is preferably 2.0 or less, more preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.0 or less. Since the smaller the yellowness index (YI), the less coloration the ionomer resin granules have, the lower limit is not particularly limited and may be, for example, 0 or more. The yellowness index (YI) can be measured using a colorimeter in accordance with JIS Z8722:2009.

[0092] [Porous ionomer resin granules] The present invention also encompasses porous ionomer resin granules having a porosity of 60% or more. Because the porous ionomer resin granules of the present invention are ionomer resin granules having a porosity of 60% or more, they are easy to dry and handle, and the solvent in the ionomer resin granules is easily dried. The same description regarding the porosity of the ionomer resin granules obtained by the method of the present invention applies to the porosity of the porous ionomer resin granules of the present invention.

[0093] In one embodiment of the present invention, the porous ionomer resin granules of the present invention are preferably in the form of pellets having a size of 1 to 8 mm, from the viewpoint of improving ease of handling. The same description regarding the shape and size of the pellets of the porous ionomer resin granules of the present invention obtained by the method of the present invention applies to the shape and size of the pellets.

[0094] In one embodiment of the present invention, the porous ionomer resin granules of the present invention preferably have a median pore diameter of 0.05 to 1.2 μm, from the viewpoint of easily improving the strength and handleability of the granules. The same description regarding the median pore diameter of the porous ionomer resin granules of the present invention applies to the median pore diameter of the ionomer resin granules obtained by the method of the present invention.

[0095] In one embodiment of the present invention, the content of the salt of a strong acid and a strong base in the porous ionomer resin granules of the present invention is preferably 1,000 mg / kg or less, from the viewpoint of easily improving the transparency of the ionomer resin granules, particularly the transparency after water absorption. The same description regarding the type and content of the salt in the porous ionomer resin granules obtained by the method of the present invention applies to the type and content of the salt in the porous ionomer resin granules of the present invention.

[0096] In a preferred embodiment of the present invention, the porous ionomer resin granules of the present invention are preferably the above-mentioned ionomer resin granules obtained by the method of the present invention, and the description regarding the ionomer resin granules obtained by the method of the present invention described in the section <Ionomer resin granules> applies equally.

[0097] [Resin Composition] If necessary, additives may be added to the ionomer resin granules obtained by the method of the present invention or the porous ionomer resin granules of the present invention to form a resin composition. The resin composition of the present invention comprises the ionomer resin granules obtained by the method of the present invention or the porous ionomer resin granules of the present invention and additives. Examples of optional additives include ultraviolet absorbers, antioxidants, antioxidants, heat degradation inhibitors, light stabilizers, anti-sticking agents, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, dyes and pigments, organic dyes, matting agents, and fluorescent materials. These additives may be used alone or in combination of two or more. Among these additives, ultraviolet absorbers, antioxidants, antioxidants, heat degradation inhibitors, light stabilizers, anti-sticking agents, lubricants, mold release agents, polymer processing aids, and organic dyes are preferred.

[0098] An ultraviolet absorber is a compound capable of absorbing ultraviolet rays, and is said to have the function of converting light energy into heat energy. Examples of ultraviolet absorbers include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, oxalic acid anilides, malonic acid esters, and formamidines. These may be used alone or in combination of two or more.

[0099] Benzotriazoles are preferred as ultraviolet absorbers because they are highly effective in suppressing deterioration of optical properties, such as coloration, due to exposure to ultraviolet light. Preferred examples of benzotriazoles include 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (manufactured by BASF; trade name: TINUVIN 329), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (manufactured by BASF; trade name: TINUVIN 234), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-t-octylphenol] (manufactured by ADEKA Corporation; trade name: Adekastab LA-31), and 2-(5-octylthio-2H-benzotriazol-2-yl)-6-tert-butyl-4-methylphenol. These may be used alone or in combination of two or more.

[0100] Examples of triazine ultraviolet absorbers include 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine (manufactured by ADEKA Corporation; trade name: Adekastab LA-F70), its analogues, hydroxyphenyltriazine ultraviolet absorbers (manufactured by BASF; trade names: TINUVIN 477 and TINUVIN 460), and 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine. These may be used alone or in combination of two or more.

[0101] Examples of the antioxidant include known materials. Specific examples of the antioxidant include phenolic compounds such as hydroquinone, hydroquinone monomethyl ether, 2,5-di-t-butylphenol, 2,6-di(t-butyl)-4-methylphenol, and mono(or di- or tri)(α-methylbenzyl)phenol; bisphenol compounds such as 2,2′-methylenebis(4-ethyl-6-t-butylphenol), 4,4′-butylidenebis(3-methyl-6-t-butylphenol), and 4,4′-thiobis(3-methyl-6-t-butylphenol); benzimidazole compounds such as 2-mercaptobenzimidazole and 2-mercaptomethylbenzimidazole; amine-ketone compounds such as 2,2,4-trimethyl-1,2-dihydroquinoline, reaction products of diphenylamine and acetone, and 2,2,4-trimethyl-1,2-dihydroquinoline polymers; aromatic secondary amine compounds such as N-phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, p-(p-toluenesulfonylamido)diphenylamine, and N,N'-diphenyl-p-phenylenediamine; and thiourea compounds such as 1,3-bis(dimethylaminopropyl)-2-thiourea and tributylthiourea. These may be used alone or in combination of two or more.

[0102] The antioxidant is effective in preventing oxidative degradation of the resin by itself in the presence of oxygen. Examples include phosphorus-based antioxidants, hindered phenol-based antioxidants, and thioether-based antioxidants. These antioxidants may be used alone or in combination of two or more. Among them, from the viewpoint of the effect of preventing degradation of optical properties due to coloring, phosphorus-based antioxidants and hindered phenol-based antioxidants are preferred, and a combination of a phosphorus-based antioxidant and a hindered phenol-based antioxidant is more preferred.

[0103] When a phosphorus-based antioxidant and a hindered phenol-based antioxidant are used in combination, the mass ratio of the phosphorus-based antioxidant to the hindered phenol-based antioxidant is preferably 1:5 to 2:1, and more preferably 1:2 to 1:1.

[0104] Preferred examples of the phosphorus-based antioxidant include 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite (manufactured by ADEKA Corporation; trade name: Adekastab HP-10), tris(2,4-di-t-butylphenyl)phosphite (manufactured by BASF; trade name: IRGAFOS168), and 3,9-bis(2,6-di-t-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (manufactured by ADEKA Corporation; trade name: Adekastab PEP-36). These may be used alone or in combination of two or more.

[0105] Examples of preferred hindered phenol-based antioxidants include pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by BASF; trade name: IRGANOX 1010) and octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (manufactured by BASF; trade name: IRGANOX 1076). These may be used alone or in combination of two or more.

[0106] The thermal degradation inhibitor can prevent thermal degradation of a resin by capturing polymer radicals that are generated when the resin is exposed to high heat in a substantially oxygen-free state. Preferred examples of the thermal degradation inhibitor include 2-t-butyl-6-(3'-t-butyl-5'-methyl-hydroxybenzyl)-4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd.; trade name: Sumilizer GM) and 2,4-di-t-amyl-6-(3',5'-di-t-amyl-2'-hydroxy-α-methylbenzyl)phenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd.; trade name: Sumilizer GS). These may be used alone or in combination of two or more.

[0107] Light stabilizers are compounds that are said to have the function of capturing radicals generated primarily by oxidation due to light. Preferred examples of light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton. These may be used alone or in combination of two or more.

[0108] Examples of the anti-sticking agent include salts or esters of fatty acids, esters of polyhydric alcohols, inorganic salts, inorganic oxides, and particulate resins. Preferred examples of the anti-sticking agent include calcium stearate, calcium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, silicon dioxide (manufactured by Evonik; trade name: Aerosil), particulate acrylic resins, and the like. These may be used alone or in combination of two or more.

[0109] Examples of lubricants include stearic acid, behenic acid, stearamidic acid, methylene bisstearamide, hydroxystearic acid triglyceride, paraffin wax, ketone wax, octyl alcohol, hardened oil, etc. These may be used alone or in combination of two or more.

[0110] Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol, and higher fatty acid esters of glycerin such as stearate monoglyceride and stearate diglyceride. These may be used alone or in combination of two or more.

[0111] Polymer processing aids are typically produced by emulsion polymerization and comprise polymer particles with a particle size of 0.05 to 0.5 μm. These polymer particles may be single-layer particles composed of a polymer with a single composition ratio and a single intrinsic viscosity, or multi-layer particles composed of two or more polymers with different composition ratios or intrinsic viscosities. These particles may be composed of one type alone or a combination of two or more types. Among these, preferred are particles with a two-layer structure, having an inner polymer layer with a low intrinsic viscosity and an outer polymer layer with a high intrinsic viscosity of 5 dl / g or more. The intrinsic viscosity of the polymer processing aid is preferably 3 to 6 dl / g. If the intrinsic viscosity is too low, the effect of improving moldability tends to be low, while if the intrinsic viscosity is too high, the moldability of the copolymer tends to be reduced.

[0112] As an example of the organic dye, a compound having a function of converting ultraviolet light into visible light is preferably used. The organic dye may be used alone or in combination of two or more kinds.

[0113] Examples of fluorescent substances include fluorescent pigments, fluorescent dyes, fluorescent white dyes, fluorescent brightening agents, fluorescent bleaches, etc. These may be used alone or in combination of two or more.

[0114] The content of the various additives can be appropriately selected within a range that does not impair the effects of the present invention, and the total content of the various additives is preferably 7 mass % or less, more preferably 5 mass % or less, and even more preferably 4 mass % or less, relative to the total mass of the resin composition.

[0115] In one embodiment of the present invention, the content of the ionomer resin granules obtained by the method of the present invention or the porous ionomer resin granules of the present invention is, from the viewpoint of easily improving transparency and handleability, preferably 90 mass% or more, more preferably 95 mass% or more, even more preferably 98 mass% or more, and even more preferably 99 mass% or more, relative to the total mass of the resin composition, and is preferably 100 mass% or less, more preferably 99.99 mass% or less.

[0116] The various additives may be added when the ionomer resin granules are produced, or after the ionomer resin granules are produced, or may be added when the resin sheet described below is produced.

[0117] The resin composition of the present invention may be in a granular form such as pellets to improve convenience during storage, transportation, or molding. The resin composition can be pelletized, for example, by cutting strands obtained by melt extrusion. When pelletizing by melt extrusion, the temperature of the resin or resin composition during melt extrusion is preferably 150°C or higher, more preferably 170°C or higher, from the viewpoint of facilitating stable discharge from the extruder. Furthermore, the temperature is preferably 250°C or lower, more preferably 230°C or lower, from the viewpoint of preventing thermal decomposition and deterioration of the resin. The ionomer resin granules of the present invention and the resin composition of the present invention emit fewer volatile substances and are less likely to generate odors when pelletized by melt extrusion, thereby preventing deterioration of the working environment.

[0118] [Resin Sheet] The present invention also includes a resin sheet comprising one or more layers containing the porous ionomer resin granules of the present invention as a resin component. The resin sheet of the present invention has excellent transparency because it comprises a layer containing the porous ionomer resin granules of the present invention as a resin component.

[0119] The resin sheet of the present invention includes one or more layers (hereinafter also referred to as layer (x)) containing the porous ionomer resin granules of the present invention as a resin component. Layer (x) is a layer containing the porous ionomer resin granules of the present invention and, optionally, additives. The resin sheet of the present invention may be composed of only layer (x), or may be a laminate containing at least one layer (x). The laminate is not particularly limited, but examples include a laminate containing two or more layers (x), and a laminate containing one or more layers (x) and one or more other layers. When layer (x) or other layers are multiple layers, the resin granules or resin compositions constituting each layer may be the same or different.

[0120] Examples of the other layer include layers containing known resins. Examples of the resin include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, polytetrafluoroethylene, acrylic resin, polyamide, polyacetal, polycarbonate, and polyesters such as polyethylene terephthalate, polybutylene terephthalate, cyclic polyolefin, polyphenylene sulfide, polytetrafluoroethylene, polysulfone, polyethersulfone, polyarylate, liquid crystal polymer, polyimide, and thermoplastic elastomer. Furthermore, the other layer may also contain one or more additives such as the additives described above, as well as plasticizers, pigments, dyes, heat-shielding materials (e.g., inorganic heat-shielding particles or organic heat-shielding materials having infrared absorbing properties), and functional inorganic compounds, if necessary.

[0121] In one embodiment of the present invention, from the viewpoint of excellent bubble removal properties when the resin sheet and the substrate are thermocompression bonded, the resin sheet of the present invention preferably has an uneven structure on the surface by a conventionally known method such as melt fracture or embossing. The shape of the melt fracture and embossing may be appropriately selected from conventionally known methods.

[0122] The thickness of each layer (x) in the resin sheet of the present invention is preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, particularly preferably 0.4 mm or more, and is preferably 5 mm or less, more preferably 4 mm or less, even more preferably 2 mm or less, particularly preferably 1 mm or less. When the resin sheet has multiple layers (x), the thicknesses of the multiple layers (x) in the resin sheet may be the same or different.

[0123] The thickness of the resin sheet of the present invention is preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, still more preferably 0.4 mm or more, particularly preferably 0.5 mm or more, especially more preferably 0.6 mm or more, especially more preferably 0.7 mm or more, and particularly preferably 0.75 mm or more, and is also preferably 20 mm or less, more preferably 15 mm or less, even more preferably 10 mm or less, even more preferably 5 mm or less, especially preferably 4 mm or less, especially more preferably 2 mm or less, and especially more preferably 1 mm or less.

[0124] The thickness of the resin sheet is measured by a conventionally known method, for example, using a contact or non-contact thickness meter, etc. The resin sheet may be in a state of being wound into a roll or in a state of individual sheets.

[0125] In a preferred embodiment of the present invention, the resin sheet of the present invention exhibits the same storage modulus at 50°C, haze, water absorption haze, annealing haze, and yellowness index as the ionomer resin granules obtained by the method of the present invention described in the section <Ionomer Resin Granules>.

[0126] The resin sheet of the present invention preferably has a low water content, from the viewpoint of being less likely to foam during the production of laminated glass. The water content of the resin sheet is preferably 1% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.02% by mass or less, and particularly preferably 0.01% by mass or less. The water content can be measured by coulometric titration.

[0127] The method for producing the resin sheet of the present invention is not particularly limited. For example, the porous ionomer resin granules of the present invention or the resin composition of the present invention can be uniformly kneaded, and then the layer (x) can be produced by a known film-forming method such as extrusion, calendaring, pressing, solution casting, melt casting, or inflation. The layer (x) may be used alone as a resin sheet. Furthermore, if necessary, two or more layers (x), or one or more layers (x) and one or more other layers may be laminated by press molding or the like to form a laminated resin sheet. Alternatively, two or more layers (x), or one or more layers (x) and one or more other layers may be molded by co-extrusion to form a laminated resin sheet. When the layer (x) or other layers are multiple layers, the resin compositions constituting each layer may be the same or different.

[0128] Among known film-forming methods, a method of producing a resin sheet using an extruder is preferably used. The resin temperature during extrusion is preferably 150°C or higher, more preferably 170°C or higher, from the viewpoint of facilitating stabilization of the resin discharge from the extruder and reducing mechanical troubles. The resin temperature during extrusion is preferably 250°C or lower, more preferably 230°C or lower, from the viewpoint of facilitating reduction of resin decomposition and degradation of the resin associated with decomposition. In addition, in order to efficiently remove volatile substances, it is preferable to remove the volatile substances from the vent port of the extruder by reducing pressure.

[0129] [Laminated Glass Interlayer Film and Laminated Glass] The resin sheet of the present invention can be suitably used as a laminated glass interlayer film (also simply referred to as an interlayer film). Thus, the present invention encompasses a laminated glass interlayer film made of the resin sheet of the present invention. The present invention also encompasses laminated glass having two glass plates and the laminated glass interlayer film of the present invention disposed between the two glass plates. The laminated glass of the present invention can have excellent transparency because it has a laminated glass interlayer film made of the resin sheet.

[0130] Examples of glass plates to be laminated with the interlayer film of the present invention include inorganic glass such as float glass, polished glass, figured glass, wired glass, and heat-absorbing glass, as well as conventionally known organic glass such as polymethyl methacrylate and polycarbonate. These may be colorless or colored. One type of these may be used, or two or more types may be used in combination. Furthermore, the thickness of one glass plate is preferably 100 mm or less, and the thicknesses of the two glass plates may be the same or different.

[0131] The laminated glass of the present invention, which is obtained by sandwiching the resin sheet between two pieces of glass, can be produced by a conventionally known method. Examples of such methods include a method using a vacuum laminator, a method using a vacuum bag, a method using a vacuum ring, a method using a nip roll, etc. Another example is a method in which the glass sheets are temporarily pressure-bonded by the above method, and then placed in an autoclave for final bonding.

[0132] When using a vacuum laminator, for example, 1 × 10 －６ ~1 x 10 －１ Laminated glass can be produced by laminating glass sheets, an interlayer film, and an optional layer (such as an adhesive resin layer) under a reduced pressure of 60 to 200°C, particularly 80 to 160°C, of ​​a pressure of about 2 × 10 MPa. A method using a vacuum bag or a vacuum ring is described, for example, in European Patent No. 1235683. －２ ~3 x 10 －２ Laminated glass can be produced by laminating glass sheets, an interlayer film, and any optional layers at 100 to 160° C. under a pressure of about 100 MPa.

[0133] An example of a manufacturing method using nip rolls is a method in which a glass plate, an interlayer film, and any optional layers are laminated, degassed with rolls at a temperature below the flow initiation temperature of the interlayer film, and then pressure-bonded at a temperature close to the flow initiation temperature. Specifically, for example, a method in which the laminate is heated to 30 to 70°C using an infrared heater or the like, degassed with rolls, further heated to 50 to 120°C, and then pressure-bonded with rolls is exemplified.

[0134] When the laminated glass is subjected to pressure bonding by the above-mentioned method and then placed in an autoclave for further pressure bonding, the operating conditions for the autoclave step are appropriately selected depending on the thickness and configuration of the laminated glass. For example, it is preferable to treat the laminated glass under a pressure of 0.5 to 1.5 MPa at 100 to 160°C for 0.5 to 3 hours.

[0135] The ionomer resin granules of the present invention and the resin sheet of the present invention have high transparency and high adhesion to glass, so the laminated glass of the present invention has excellent transparency. In one embodiment of the present invention, the haze of the laminated glass of the present invention is preferably 1.0% or less, more preferably 0.8% or less, and even more preferably 0.5% or less. Since the smaller the haze, the higher the transparency of the laminated glass, the lower limit is not particularly limited and may be, for example, 0.01%. The haze of the laminated glass is measured using a haze meter in accordance with JIS K7136:2000.

[0136] The laminated glass of the present invention also has excellent transparency during annealing. The transparency during annealing can be evaluated by the haze during annealing (annealing haze). The annealing haze of the laminated glass of the present invention is preferably 5.0% or less, more preferably 4.0% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, and particularly preferably 2.0% or less. Since the smaller the haze, the higher the transparency of the laminated glass, so the lower limit is not particularly limited and may be, for example, 0.01% or more. The annealing haze of the laminated glass is determined by heating the laminated glass to 140°C, and then annealing it from 140°C to 23°C at a rate of 0.1°C / min, and then measuring the haze using a haze meter in accordance with JIS K7136:2000, and can be determined, for example, by the method described in the Examples.

[0137] The laminated glass of the present invention is preferably little colored and as colorless as possible. The yellowness index (YI) of the laminated glass of the present invention is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.5 or less, particularly preferably 1.0 or less, and may preferably be 0 or more. The yellowness index (YI) can be measured using a colorimeter in accordance with JIS Z8722.

[0138] The adhesive strength between the glass plates and the interlayer film in the laminated glass of the present invention is measured, for example, by the compression shear strength test described in WO 1999-058334. From the viewpoint of easily increasing the adhesive strength, the compressive shear strength is preferably 15 MPa or more, more preferably 20 MPa or more, and particularly preferably 25 MPa or more. Furthermore, from the viewpoint of easily increasing the penetration resistance of the laminated glass, the compressive shear strength may be 50 MPa or less.

[0139] As described above, a resin sheet comprising one or more layers containing the ionomer resin granules of the present invention as a resin component is useful as an interlayer film for laminated glass. The interlayer film for laminated glass is particularly preferred as an interlayer film for laminated glass for structural materials (facades) because of its excellent adhesion to substrates such as glass, transparency, and self-supporting properties.

[0140] Furthermore, the laminated glass of the present invention is not limited to being used as an interlayer film in laminated glass for structural materials, and can also be suitably used for automobile windshields, automobile side glass, automobile sunroofs, automobile rear glass, glass for head-up displays, laminates for exterior walls and roofs, panels, doors, windows, walls, roofs, sunroofs, soundproof walls, display windows, balconies, handrail walls and other building materials, conference room partition glass components, solar panels, etc.

[0141] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0142] [Contents of Each Monomer Unit in Crude Ionomer Resin and Raw Material Resin] For the ionomer resin pellets obtained in the Examples and Comparative Examples, the contents of each of the monomer units, i.e., (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B), ethylene units (C), and (meth)acrylic acid ester units (D), in the ionomer resin pellets were determined by analysis as follows. Each content corresponds to the content of each monomer unit in the crude ionomer resin in the Examples and Comparative Examples.

[0143] The ionomer resin pellets obtained in each of the examples and comparative examples were dissolved in a mixed solvent of dehydrated toluene / dehydrated acetic acid (75 / 25% by mass), reacted at 100°C for 2 hours, and then reprecipitated in a mixed solvent of acetone / water (80 / 20% by mass), thereby converting the (meth)acrylic acid neutralized unit (B) into the (meth)acrylic acid unit (A). The obtained resin was thoroughly washed with water and then dried, and the dried resin was subjected to the following (1) to (3). (1) The components of the monomer units constituting the resin were analyzed by pyrolysis GC-MS. (2) The acid value of the resin was measured in accordance with JIS K0070:1992. (3) The acid value of the resin was measured using a mixed solvent of deuterated toluene and deuterated methanol. １ H-NMR (400 MHz, manufactured by JEOL Ltd.) measurements were performed. (4) Furthermore, the ionomer resin pellets obtained in the examples and comparative examples were each subjected to microwave decomposition pretreatment with nitric acid, and then the type and amount of metal ions in the (meth)acrylic acid neutralization unit (B) were identified by ICP optical emission spectrometry (Thermo Fisher Scientific iCAP6500Duo). From the above (1), the type and structure of the (meth)acrylic acid ester unit (D) and the (meth)acrylic acid unit (A) were identified. From this information and the information from the above (2) and (3), the ratio of ethylene unit (C) / (meth)acrylic acid ester unit (D) / (total of (meth)acrylic acid unit (A) and (meth)acrylic acid neutralization unit (B)) was calculated. Furthermore, the ratio of ethylene unit (C) / (meth)acrylic acid ester unit (D) / (meth)acrylic acid unit (A) / (meth)acrylic acid neutralized product unit (B) was calculated from the information in (4) above. The content of each monomer unit in the raw material ethylene-(meth)acrylic acid ester copolymer (X) was measured by dissolving the copolymer in deuterated toluene or deuterated THF, １ Measurements were performed using H-NMR (400 MHz, manufactured by JEOL Ltd.) and calculations were made.

[0144] [Melt flow rate (MFR) of raw material resin] The melt flow rate of the raw material resin used in the examples and comparative examples was measured in accordance with JIS K7210-1: 2014. Specifically, each resin was melted in a cylinder and extruded through a die with a nominal hole diameter of 2.095 mm installed at the bottom of the cylinder under conditions of 190°C and a load of 2.16 kg, and the amount of resin extruded per 10 minutes (g / 10 minutes) was measured.

[0145] [Pellet Porosity and Median Pore Diameter] After freeze-drying the pellets obtained in the Examples and Comparative Examples at -80°C, 0.5 g was placed in a standard 5 cc powder cell (stem volume 0.4 cc) and measured for pellet porosity and median pore diameter using a Micromeritics pore distribution analyzer (Shimadzu Corporation, Autopore V9620) under an initial pressure of 2.6 kPa. The median pore diameter is the median diameter (d50) for all pores in the log differential pore volume distribution with a pore diameter in the range of 0.005 to 100 μm. The mercury parameters were a mercury contact angle of 130 degrees and a mercury surface tension of 485 hynes / cm.

[0146] [Pellet Size] The pellet size of the pellets obtained in the Examples and Comparative Examples was calculated using the following procedure. Ten pellets were randomly selected from the obtained pellets, and for each of the ten pellets, the pellet height (as the X-axis length (Lx)), the Y-axis length (Ly) of the longest part of the diameter at the bottom of the pellet, and the Z-axis length (Lz) of the shortest part of the diameter at the bottom of the pellet were measured using a micrometer. The average value of the X-axis, Y-axis, and Z-axis lengths of each pellet ((Lx + Ly + Lz) / 3) was calculated. The arithmetic mean value of the average values ​​of the X-axis, Y-axis, and Z-axis lengths of each pellet was taken as the pellet size.

[0147] [Handling] The handling of the pellets obtained in the Examples and Comparative Examples was evaluated according to the following criteria, depending on the strength of the resin extruded from the die into the poor solvent and whether it could be pelletized. Rating A: The extruded resin was in the form of strands. The strands were not broken when lifted, and pelletization was possible. Rating C: The extruded resin was in the form of strands. The strands were broken when lifted, but pelletization was possible. Rating X: The extruded resin was not in the form of strands, and pelletization was not possible.

[0148] [Content of Salts Composed of Strong Acids and Strong Bases (Amount of Residual Inorganic Salts)] 0.1 g of each of the crude ionomer resin and ionomer resin pellets obtained in the Examples and Comparative Examples was weighed out, 10 mL of ultrapure water was added, and the mixture was heated at 90°C for 1 hour. The mixture was then allowed to cool and filtered through a filter with a mesh size of 0.45 μm. The filtrate obtained by filtration was used as a sample liquid and measured using an ion chromatograph (manufactured by Shimadzu Corporation) under the following conditions. The amount of chloride ions or nitrate ions was determined based on the peak area obtained in the measurement, and the amount of chloride ions or nitrate ions was converted into the amount of sodium salt to determine the amount of residual inorganic salts. (Measurement Conditions) Eluent: Mixed solution of aqueous sodium carbonate solution (0.6 mmol / L) and aqueous sodium bicarbonate solution (12 mmol / L); Flow rate: 1.0 mL / min; Column temperature: 40°C; Column: IC-SA2 (250 L x 4.0)

[0149] [Transparency upon Water Absorption (Water Absorption Haze)] The ionomer resin pellets obtained in the Examples and Comparative Examples were melt-kneaded at 210°C, and the melt-kneaded mixture was heated at 210°C and subjected to a pressure of 4.9 MPa (50 kgf / cm ２ ) for 5 minutes to obtain a resin sheet having a thickness of 0.8 mm. The obtained resin sheet was cut into a 50 mm square, and the cut sample was immersed in ion-exchanged water at 23 ° C. for 300 hours to obtain a water-absorbed sample. After wiping off the moisture adhering to the surface of the water-absorbed sample taken out of the ion-exchanged water, the haze of the water-absorbed sample was measured in accordance with JIS K7136:2000 using a haze meter HZ-1 (manufactured by Suga Test Instruments Co., Ltd.).

[0150] [Transparency upon annealing (annealing haze)] The resin sheet obtained in the same manner as above was sandwiched between two 2.7 mm thick float glass sheets, and a vacuum laminator (Nisshinbo Mechatronics Inc. 1522N) was used to reduce the pressure inside the vacuum laminator at 100 ° C. for 1 minute, and then pressed at 30 kPa for 5 minutes while maintaining the reduced pressure and temperature to obtain a temporary bonded body. The obtained temporary bonded body was placed in an autoclave and treated at 140 ° C. and 1.2 MPa for 30 minutes to obtain a laminated glass. The obtained laminated glass was heated to 140 ° C. and then annealed to 23 ° C. at a rate of 0.1 ° C. / min. The haze of the laminated glass after the annealing operation was measured in accordance with JIS K7136:2000 using a haze meter HZ-1 (manufactured by Suga Test Instruments Co., Ltd.).

[0151] [Raw Material Resins] In the Examples and Comparative Examples, the amount of modification with methyl methacrylate (MMA) or ethyl acrylate (EA) and MFR of each ethylene-(meth)acrylic acid ester copolymer (X) used as a raw material are shown in Table 1. "Aclift" (registered trademark) WK307 manufactured by Sumitomo Chemical Co., Ltd. was used as EMMA1, and NUC-6070 manufactured by NUC Corporation was used as EEA1.

[0152]

[0153] Example 1: 100 parts by weight of EMMA1 (Table 1) was placed in a stainless steel pressure vessel, and 233 parts by weight of toluene was added. The mixture was stirred at 60°C under a pressure of 0.02 MPa to dissolve EMMA1. 96 parts by weight of a 20% by weight solution of sodium hydroxide in methanol was added to the resulting solution, and the mixture was stirred at 100°C for 4 hours to saponify EMMA1, converting some of the methyl methacrylate units to sodium methacrylate units. The solution was then cooled to 50°C, after which 92 parts by weight of nitric acid (30% by weight) was added. The mixture was stirred at 50°C for 1 hour to convert some of the sodium methacrylate units to methacrylic acid, yielding a crude ionomer resin solution (1). The degree of saponification of the crude ionomer resin was 96%, and the degree of neutralization was 24%. The obtained crude ionomer resin solution (1) was heated to 60°C, and 97 parts by mass of toluene and 32 parts by mass of methanol were added to dilute the crude ionomer resin to a concentration of 15% by mass. The 60°C mixture of crude ionomer resin and solvent obtained above was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and solidified to obtain a strand-shaped resin. The obtained strand could be wound by hand, and its handleability was rated A. The obtained strand was cut with a fan cutter (manufactured by Hoshi Plastic Co., Ltd.) to obtain 3 mm-sized resin pellets 1-1. Next, 100 parts by mass of the obtained resin pellets were mixed with 600 parts by mass of a water / methanol (50 / 50% by mass) mixed solvent. The slurry obtained by the above mixture was stirred at 40°C for 1 hour, and then the resin pellets were collected by filtration at room temperature. The resin pellets were washed three more times with a mixed solvent of water / methanol (50 / 50% by mass) to obtain washed ionomer resin pellets 1-2. The obtained ionomer resin pellets 1-2 had the same porosity, median pore diameter, and pellet size as resin pellets 1-1.

[0154] Example 2 The crude ionomer resin solution (1) obtained in Example 1 was adjusted to 50°C, and 342 parts by mass of toluene and 114 parts by mass of methanol were added thereto to dilute the crude ionomer resin to a concentration of 10% by mass. The 50°C mixture of crude ionomer resin and solvent obtained above was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and coagulated to obtain a strand-shaped resin. The obtained strand could be wound by hand, and its handleability was evaluated as A. The obtained strand was cut into 3 mm-sized resin pellets 2-1. The obtained resin pellets 2-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 2-2. The obtained ionomer resin pellets 2-2 had the same porosity, median pore diameter, and pellet size as resin pellets 2-1.

[0155] Example 3: 100 parts by weight of EMMA1 (Table 1) was placed in a stainless steel pressure vessel, and 233 parts by weight of toluene was added. The mixture was stirred at 60°C under a pressure of 0.02 MPa to dissolve EMMA1. 96 parts by weight of a 20% by weight solution of sodium hydroxide in methanol was added to the resulting solution, and the mixture was stirred at 100°C for 4 hours to saponify EMMA1, converting some of the methyl methacrylate units to sodium methacrylate units. The solution was then cooled to 50°C, after which 81 parts by weight of 20% by weight of hydrochloric acid was added, and the mixture was stirred at 50°C for 1 hour to convert some of the sodium methacrylate units to methacrylic acid, yielding a crude ionomer resin solution (2). The degree of saponification of the crude ionomer resin was 96%, and the degree of neutralization was 22%. The obtained crude ionomer resin solution (2) was diluted with 351 parts by mass of toluene and 117 parts by mass of methanol to a crude ionomer resin concentration of 10% by mass. The 50°C mixture of crude ionomer resin and solvent obtained above was extruded through a 2 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and solidified to obtain a strand-shaped resin. The obtained strand could be wound by hand, and its handleability was rated A. The obtained strand was cut with a fan cutter (manufactured by Hoshi Plastic Co., Ltd.) to obtain 5 mm-sized resin pellets 3-1. The obtained resin pellets 3-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 3-2. The obtained ionomer resin pellets 3-2 had the same porosity, median pore diameter, and pellet size as resin pellets 3-1.

[0156] Example 4 The crude ionomer resin solution (2) obtained in Example 3 was adjusted to 60°C, and 106 parts by mass of toluene and 35 parts by mass of methanol were added to dilute the crude ionomer resin to a concentration of 15% by mass. The 60°C mixture of crude ionomer resin and solvent obtained above was extruded through a 1.5 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and coagulated to obtain a strand-shaped resin. The resulting strand could be wound by hand, and its handleability was rated A. The resulting strand was cut to obtain 4 mm-sized resin pellets 4-1. The resulting resin pellets 4-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 4-2. The resulting ionomer resin pellets 4-2 had the same porosity, median pore diameter, and pellet size as resin pellets 4-1.

[0157] Example 5 The crude ionomer resin solution (1) obtained in Example 1 was adjusted to 50°C, and 97 parts by mass of toluene and 32 parts by mass of methanol were added to dilute the crude ionomer resin to a concentration of 15% by mass. The 50°C mixture of crude ionomer resin and solvent obtained above was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into methanol at 5°C and coagulated to obtain a strand-shaped resin. The resulting strand could be wound by hand, and its handleability was rated A. The resulting strand was cut to obtain 3 mm-sized resin pellets 5-1. The resulting resin pellets 5-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 5-2. The resulting ionomer resin pellets 5-2 had the same porosity, median pore diameter, and pellet size as resin pellets 5-1.

[0158] Example 6 The crude ionomer resin solution (2) obtained in Example 3 was adjusted to 50°C, and 106 parts by mass of toluene and 35 parts by mass of methanol were added to dilute the crude ionomer resin to a concentration of 15% by mass. The 50°C mixture of crude ionomer resin and solvent obtained above was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 5°C and coagulated to obtain a strand-shaped resin. The resulting strand could be wound by hand, and its handleability was rated A. The resulting strand was cut to obtain 3 mm-sized resin pellets 6-1. The resulting resin pellets 6-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 6-2. The resulting ionomer resin pellets 6-2 had the same porosity, median pore diameter, and pellet size as resin pellets 6-1.

[0159] Example 7: 100 parts by mass of EEA1 (Table 1) was placed in a stainless steel pressure vessel, and 233 parts by mass of toluene was added. The mixture was stirred at 60°C under a pressure of 0.02 MPa to dissolve EEA1. 96 parts by mass of a 20% by mass solution of sodium hydroxide in methanol was added to the resulting solution, and the mixture was stirred at 100°C for 4 hours to saponify EEA1 and convert some of the ethyl acrylate units to sodium acrylate units. This solution was then cooled to 50°C, after which 93 parts by mass of nitric acid (30% by mass) was added, and the mixture was stirred at 50°C for 1 hour to convert some of the sodium acrylate units to acrylic acid, yielding a crude ionomer resin solution (3). The degree of saponification of the crude ionomer resin was 96%, and the degree of neutralization was 23%. The resulting crude ionomer resin solution was cooled to 40°C, and 1,020 parts by mass of toluene and 340 parts by mass of methanol were added to dilute the crude ionomer resin to a concentration of 5% by mass. The mixture of crude ionomer resin and solvent obtained above at 40°C was extruded into water at 20°C through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel and solidified, yielding a strand-like resin. The resulting strand was easily broken when attempting to wind it up by hand, and its handleability was rated C. The resulting strand was cut with a fan cutter (manufactured by Hoshi Plastics Co., Ltd.) to obtain 3 mm-sized resin pellets 7-1. The resulting resin pellets 7-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 7-2. The resulting ionomer resin pellets 7-2 had the same porosity, median pore diameter, and pellet size as resin pellets 7-1.

[0160] Example 8 The crude ionomer resin solution (3) obtained in Example 7 was cooled to 40°C, and 80 parts by mass of toluene and 27 parts by mass of methanol were added to dilute the crude ionomer resin to a concentration of 15% by mass. The resulting 40°C mixture of crude ionomer resin and solvent was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and solidified to obtain a strand-shaped resin. The resulting strand could be wound by hand, and its handleability was rated A. The resulting strand was cut with a fan cutter (manufactured by Hoshi Plastics Co., Ltd.) to obtain 3 mm-sized resin pellets 8-1. The resulting resin pellets 8-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 8-2. The resulting ionomer resin pellets 8-2 had the same porosity, median pore diameter, and pellet size as resin pellets 8-1.

[0161] Example 9: 100 parts by weight of EMMA1 (Table 1) was placed in a stainless steel pressure vessel, and 233 parts by weight of toluene was added. The mixture was stirred at 60°C under a pressure of 0.02 MPa to dissolve EMMA1. 96 parts by weight of a 20% by weight solution of sodium hydroxide in methanol was added to the resulting solution, and the mixture was stirred at 100°C for 4 hours to saponify EMMA1, converting some of the methyl methacrylate units to sodium methacrylate units. The solution was then cooled to 50°C, after which 95 parts by weight of 20% by weight of hydrochloric acid was added, and the mixture was stirred at 50°C for 1 hour to convert some of the sodium methacrylate units to methacrylic acid, yielding a crude ionomer resin solution (4). The degree of saponification of the crude ionomer resin was 96%, and the degree of neutralization was 20%. The resulting crude ionomer resin solution (4) was diluted with 96 parts by mass of toluene and 32 parts by mass of methanol to a crude ionomer resin concentration of 15% by mass. The resulting 50°C mixture of crude ionomer resin and solvent was extruded through a 2 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and solidified to obtain a strand-shaped resin. The resulting strand could be wound by hand, and its handleability was rated A. The resulting strand was cut with a fan cutter (manufactured by Hoshi Plastics Co., Ltd.) to obtain 3 mm-sized resin pellets 9-1. The resulting resin pellets 9-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 9-2. The resulting ionomer resin pellets 9-2 had the same porosity, median pore diameter, and pellet size as resin pellets 9-1.

[0162] Comparative Example 1 The crude ionomer resin solution (1) obtained in Example 1 was adjusted to 50°C. While the crude ionomer resin concentration remained at 19% by mass, the crude ionomer resin solution (1) was extruded into water at 20°C through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel and solidified, yielding a strand-shaped resin. The resulting strand could be wound by hand, and its handleability was evaluated as A. The resulting strand was cut to obtain 3 mm-sized resin pellets 1'-1. The resulting resin pellets 1'-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 1'-2. The resulting ionomer resin pellets 1'-2 had the same porosity, median pore diameter, and pellet size as resin pellets 1'-1.

[0163] Comparative Example 2 The crude ionomer resin solution (2) obtained in Example 3 was adjusted to 70°C, and 109 parts by mass of toluene and 36 parts by mass of methanol were added thereto to dilute the crude ionomer resin to a concentration of 15% by mass. The mixture of crude ionomer resin and solvent obtained above at 70°C was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and coagulated. However, the resin foamed, and no strand-like resin could be obtained. The handleability was also rated X.

[0164] Comparative Example 3 The crude ionomer resin solution (2) obtained in Example 3 was adjusted to 50°C, and 109 parts by mass of toluene and 36 parts by mass of methanol were added thereto to dilute the crude ionomer resin to a concentration of 15% by mass. The 50°C mixture of crude ionomer resin and solvent obtained above was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 70°C in an attempt to coagulate it. However, the resin was miscible in the water, and no strand-shaped resin could be obtained. The handleability was also rated X.

[0165] Comparative Example 4 The crude ionomer resin solution (3) obtained in Example 7 was adjusted to 50°C, and 315 parts by mass of toluene and 105 parts by mass of methanol were added thereto to dilute the crude ionomer resin to a concentration of 10% by mass. The 50°C mixture of crude ionomer resin and solvent obtained above was extruded through a 1 mm diameter die attached to the bottom of a pressure-resistant vessel into water at 20°C and solidified to obtain a strand-shaped resin. The resulting strand could be wound by hand, and its handleability was rated A. The resulting strand was cut to obtain 10 mm-sized resin pellets 2'-1. The resulting resin pellets 2'-1 were then washed in the same manner as in Example 1 to obtain washed ionomer resin pellets 2'-2. The resulting ionomer resin pellets 2'-2 had the same porosity, median pore diameter, and pellet size as resin pellets 2'-1.

[0166] All pellets obtained in the Examples and Comparative Examples were cylindrical. The washed ionomer resin pellets obtained in the Examples and Comparative Examples were vacuum-dried for 8 hours or more, and then analyzed and evaluated. The analysis and evaluation results are shown in Table 2. In the table, "Tol" represents toluene, and "MeOH" represents methanol. In the table, the amount (parts by mass) of crude ionomer resin represents the amount of crude ionomer resin obtained from 100 parts by mass of raw material resin, and the salt content (parts by mass) in the crude ionomer resin represents the salt content contained in the crude ionomer resin obtained from 100 parts by mass of raw material resin.

[0167]

[0168] As shown in Table 2, the ionomer resin pellets obtained in Examples 1 to 9 had a low salt content and were excellent in transparency and handleability. On the other hand, the ionomer resin pellets obtained in Comparative Examples 1 and 4 had low transparency. Furthermore, in Comparative Examples 2 and 3, ionomer resin pellets with good handleability were not obtained.

Claims

1. A method for producing ionomer resin particles, comprising the steps of extruding a mixture containing a crude ionomer resin and a solvent, cooling the extruded mixture, and solidifying the crude ionomer resin in the mixture to obtain porous particles, wherein the crude ionomer resin contains (meth)acrylic acid units (A), (meth)acrylic acid neutralized units (B) and ethylene units (C), and the total content of the units (A) and the units (B) is 6 to 10 mol% based on all monomer units constituting the crude ionomer resin, and the porosity of the particles is 60% or more.

2. The method according to claim 1, wherein the cooling of the extruded mixture is performed by bringing the extruded mixture into contact with a poor solvent.

3. The method according to claim 1, wherein the median diameter of the pores of the particles is 0.05 to 1.2 μm.

4. The method according to claim 1, wherein the particles are pellets having a size of 1 to 8 mm.

5. The method according to claim 1, wherein the crude ionomer resin further contains (meth)acrylate units (D), and the total content of the units (A), the units (B) and the units (D) is 6 to 10 mol% based on all monomer units constituting the crude ionomer resin.

6. The method according to claim 2, wherein the poor solvent is water, alcohol, or a mixed solvent thereof.

7. The method according to claim 1, further comprising the step of washing the obtained porous particles with a washing liquid.

8. The method according to claim 7, wherein the washing liquid is water, alcohol, or a mixture thereof.

9. The method according to claim 1, wherein the content of salts composed of strong acids and strong bases in the ionomer resin particles is 1000 mg / kg or less.

10. The method according to claim 1, using an ethylene-(meth)acrylate copolymer (X) as a raw material.

11. Porous ionomer resin particles having a porosity of 60% or more.

12. The porous ionomer resin particles according to claim 11, which are pellets having a size of 1 to 8 mm.

13. The porous ionomer resin particles according to claim 11, wherein the median diameter of the pores is 0.05 to 1.2 μm.

14. The porous ionomer resin particles according to claim 11, wherein the content of salts composed of strong acids and strong bases is 1000 mg / kg or less.

15. A resin sheet comprising one or more layers containing the porous ionomer resin particles according to any one of claims 11 to 14 as a resin component.

16. An insulating glass interlayer made of the resin sheet according to claim 15.

17. An insulating glass having two glass plates and the insulating glass interlayer according to claim 16 disposed between the two glass plates.