Aqueous dispersion and laminate

Abstract

To provide an aqueous dispersion excellent in film-forming properties and coating drying properties and capable of producing a dried product excellent in water resistance and blocking resistance, and to provide a laminate having a resin layer which is a dried product of the aqueous dispersion.SOLUTION: The aqueous dispersion contains the first resin particles and water. The first resin particles contain a first ethylene-unsaturated carboxylic acid copolymer that is a polymer of a first monomer component containing ethylene and a first unsaturated carboxylic acid, and a second ethylene-unsaturated carboxylic acid copolymer that is a polymer of a second monomer component containing ethylene and a second unsaturated carboxylic acid. The content ratio of the first unsaturated carboxylic acid and the content ratio of the second unsaturated carboxylic acid are predetermined ratios. The first resin particles have a specific content of a structural unit derived from an unsaturated carboxylic acid. The carboxy groups of the first resin particles are neutralized with the first neutralizing agent and the second neutralizing agent at a specific ratio.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an aqueous dispersion and a laminate. [Background technology]

[0002] BACKGROUND ART Conventionally, in various industrial fields, it is known to form a coating layer on the surface of a substrate (for example, a plastic film, a vapor-deposited film, a metal foil, paper, or a nonwoven fabric) in order to impart various physical properties to the surface.

[0003] As a material for forming such a coating layer, for example, an aqueous dispersion containing an ethylene-methacrylic acid copolymer having a methacrylic acid content of 15% by mass, and an ethylene-methacrylic acid copolymer having a methacrylic acid content of 10% by mass, in which a carboxy group derived from the methacrylic acid is neutralized with sodium hydroxide, and water has been proposed (see, for example, aqueous dispersion 1 in Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 014588 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, aqueous dispersions are required to have film-forming properties and coating drying properties depending on the application and purpose, and dried products produced from such aqueous dispersions are required to have water resistance and blocking resistance.

[0006] The present invention provides an aqueous dispersion that is excellent in film-forming properties and coating drying properties and that can produce a dried product that is excellent in water resistance and blocking resistance, and a laminate that includes a resin layer that is a dried product of the aqueous dispersion. [Means for solving the problem]

[0007] The present invention [1] comprises first resin particles and water, the first resin particles comprising a first ethylene-unsaturated carboxylic acid copolymer and a second ethylene-unsaturated carboxylic acid copolymer, the first ethylene-unsaturated carboxylic acid copolymer being a polymer of a first monomer component comprising ethylene and a first unsaturated carboxylic acid, the content of the first unsaturated carboxylic acid being 12% by mass or more and 30% by mass or less relative to the first monomer component, and the second ethylene-unsaturated carboxylic acid copolymer being a polymer of a second monomer component comprising ethylene and a second unsaturated carboxylic acid, the content of the second unsaturated carboxylic acid being 0% by mass or more relative to the second monomer component. % and less than 12% by mass, the content of structural units derived from unsaturated carboxylic acid in the first resin particles is 5% by mass or more and 18% by mass or less, the carboxy groups of the first resin particles are neutralized with a first neutralizing agent and a second neutralizing agent, the first neutralizing agent is an alkali metal compound and the second neutralizing agent is a basic nitrogen-containing compound, the first degree of neutralization of the first resin particles with the first neutralizing agent is 5 mol % or more and 60 mol % or less, the second degree of neutralization of the first resin particles with the second neutralizing agent is 1 mol % or more and 55 mol % or less, and the mass ratio of the first neutralizing agent to the second neutralizing agent is 2 or more and 25 or less.

[0008] The present invention [2] further includes second resin particles, the second resin particles including a third ethylene-unsaturated carboxylic acid copolymer, the second resin particles having a content of structural units derived from unsaturated carboxylic acid of 12% by mass or more and 30% by mass or less, the content of structural units derived from unsaturated carboxylic acid in the second resin particles being greater than the content of structural units derived from unsaturated carboxylic acid in the first resin particles, and carboxy groups of the second resin particles being neutralized by the first neutralizing agent and the second neutralizing agent. The aqueous dispersion includes the aqueous dispersion described in [1] above, wherein the second resin particles are neutralized with the first neutralizing agent, the third degree of neutralization of the second resin particles with the first neutralizing agent is 5 mol % or more and 60 mol % or less, the fourth degree of neutralization of the second resin particles with the second neutralizing agent is 1 mol % or more and 55 mol % or less, the mass ratio of the first neutralizing agent to the second neutralizing agent is 2 or more and 25 or less, and the content of the second resin particles is 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the total amount of the first resin particles and the second resin particles.

[0009] The present invention [3] includes the aqueous dispersion according to the above [1] or [2], in which the second degree of neutralization is 1% or more and 15% or less.

[0010] The present invention [4] includes a substrate and a resin layer in this order toward one side in the thickness direction, The resin layer includes a laminate that is a dried product of the aqueous dispersion according to any one of the above items [1] to [3]. [Effects of the Invention]

[0011] In the aqueous dispersion of the present invention, the first resin particles contain a first ethylene-unsaturated carboxylic acid copolymer and a second ethylene-unsaturated carboxylic acid copolymer, each of which has a different content of unsaturated carboxylic acid. The first resin particles contain structural units derived from unsaturated carboxylic acid in an amount of 5% by mass or more and 18% by mass or less.

[0012] The carboxy groups of the first resin particles are neutralized to a predetermined degree of neutralization by a first neutralizing agent (alkali metal compound) and a second neutralizing agent (basic nitrogen-containing compound).

[0013] Therefore, it is possible to produce a coating film that is excellent in film-forming properties and coating drying properties, as well as in water resistance and blocking resistance.

[0014] The laminate of the present invention includes a resin layer that is a dried product of the aqueous dispersion of the present invention, and therefore, can improve water resistance and blocking resistance. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of the laminate of the present invention. [Figure 2] 2A to 2C are schematic diagrams showing one embodiment of a method for producing a laminate of the present invention and a method for bonding substrates together using this laminate. Fig. 2A shows a first step of preparing a first substrate. Fig. 2B shows a second step of arranging a resin layer on one thickness-wise surface of the first substrate. Fig. 2C shows a step of arranging a second substrate on one thickness-wise surface of the resin layer and bonding the first substrate and second substrate together by thermocompression bonding. [Figure 3] 3A and 3B show a modified example of the method for producing a laminate of the present invention. Fig. 3A shows a step of disposing a resin layer on each of a first substrate and a second substrate. Fig. 3B shows a step of bonding the first substrate and the second substrate together via the resin layer. DETAILED DESCRIPTION OF THE INVENTION

[0016] The aqueous dispersion contains first resin particles and water.

[0017] <First resin particle> The first resin particles contain a first ethylene-unsaturated carboxylic acid copolymer and a second ethylene-unsaturated carboxylic acid copolymer, which have different contents of unsaturated carboxylic acid.

[0018] (First ethylene-unsaturated carboxylic acid copolymer) The first ethylene-unsaturated carboxylic acid copolymer is a resin having a relatively higher content of unsaturated carboxylic acid compared to the second ethylene-unsaturated carboxylic acid copolymer.

[0019] The first ethylene-unsaturated carboxylic acid copolymer is a polymer of a first monomer component comprising ethylene and a first unsaturated carboxylic acid.

[0020] The ethylene content relative to the first monomer component is, for example, 70% by mass to 88% by mass, preferably 78% by mass to 87% by mass, and more preferably 83% by mass to 86% by mass.

[0021] The first unsaturated carboxylic acid is a monomer having both at least one ethylenically unsaturated bond and a carboxy group. Examples of the first unsaturated carboxylic acid include monobasic acids and dibasic acids. Examples of the monobasic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of the dibasic acids include maleic acid, fumaric acid, and itaconic acid. Preferably, the first unsaturated carboxylic acid is a monobasic acid. From the viewpoints of film-forming properties and coating drying properties, more preferably, the first unsaturated carboxylic acid is methacrylic acid. That is, more preferably, the first ethylene-unsaturated carboxylic acid copolymer is a copolymer of ethylene and methacrylic acid.

[0022] The primary unsaturated carboxylic acids can be used alone or in combination of two or more kinds.

[0023] The content ratio of the first unsaturated carboxylic acid relative to the first monomer component is higher than the content ratio of the second unsaturated carboxylic acid relative to the second monomer component, which will be described later.

[0024] Specifically, the content of the first unsaturated carboxylic acid is 12% by mass to 30% by mass, preferably 13% by mass to 22% by mass, and more preferably 14% by mass to 17% by mass, relative to the first monomer component.

[0025] Specifically, the content of the first unsaturated carboxylic acid is 12% by mass or more, preferably 13% by mass or more, more preferably 14% by mass or more, and 30% by mass or less, preferably 22% by mass or less, more preferably 17% by mass or less, relative to the first monomer component.

[0026] When the content of the primary unsaturated carboxylic acid is equal to or greater than the above lower limit, the dispersion stability and coating drying properties can be improved.

[0027] On the other hand, if the content of the primary unsaturated carboxylic acid is less than the above lower limit, the dispersion stability and coating drying properties will decrease.

[0028] Furthermore, if the content of the primary unsaturated carboxylic acid is equal to or less than the above upper limit, the water resistance and blocking resistance can be improved.

[0029] On the other hand, if the content of the primary unsaturated carboxylic acid exceeds the upper limit, the water resistance and blocking resistance decrease.

[0030] The first monomer component optionally contains other monomers.

[0031] Examples of other monomers include (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include C1-12 alkyl esters of (meth)acrylic acid. Examples of C1-12 alkyl esters of (meth)acrylic acid include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, and benzyl (meth)acrylate.

[0032] The other monomers can be used alone or in combination of two or more kinds.

[0033] The content of the other monomer relative to the first monomer component is, for example, 15% by mass or less, preferably 10% by mass or less, and more preferably 0% by mass. That is, more preferably, the first monomer component does not contain any other monomer.

[0034] The polymerization of the first monomer component is not particularly limited, and a known polymerization method may be adopted, such as a method of contacting the first monomer component with a polymerization initiator (peroxide) under high temperature and high pressure conditions.

[0035] This results in a first ethylene-unsaturated carboxylic acid copolymer.

[0036] The weight average molecular weight of the first ethylene-unsaturated carboxylic acid copolymer is, for example, 8,000 to 200,000, or preferably 10,000 to 150,000, in terms of standard polystyrene measured by gel permeation chromatography (GPC).

[0037] The first ethylene-unsaturated carboxylic acid copolymer may be used alone or in combination of two or more kinds.

[0038] The content ratio of the first ethylene-unsaturated carboxylic acid copolymer is, for example, 20 parts by mass to 80 parts by mass, preferably 30 parts by mass to 70 parts by mass, and more preferably 40 parts by mass to 60 parts by mass, relative to 100 parts by mass of the total amount of the first ethylene-unsaturated carboxylic acid copolymer and the second ethylene-unsaturated carboxylic acid copolymer.

[0039] The content of the first ethylene-unsaturated carboxylic acid copolymer relative to the first resin particles is, for example, 20% by mass to 80% by mass, preferably 30% by mass to 70% by mass, and more preferably 40% by mass to 60% by mass.

[0040] (Second ethylene-unsaturated carboxylic acid copolymer) The second ethylene-unsaturated carboxylic acid copolymer is a resin having a relatively low content of unsaturated carboxylic acid compared to the first ethylene-unsaturated carboxylic acid copolymer.

[0041] The second ethylene-unsaturated carboxylic acid copolymer is a polymer of a second monomer component comprising ethylene and a second unsaturated carboxylic acid.

[0042] The ethylene content relative to the second monomer component is, for example, 70% by mass to 99% by mass, preferably 80% by mass to 97% by mass, more preferably 87% by mass to 95% by mass, and even more preferably 88% by mass to 92% by mass.

[0043] The second unsaturated carboxylic acid may be the same unsaturated carboxylic acid as the first unsaturated carboxylic acid. Preferably, the second unsaturated carboxylic acid is a monobasic acid. From the viewpoint of dispersion stability, more preferably, the second unsaturated carboxylic acid is methacrylic acid. That is, more preferably, the second ethylene-unsaturated carboxylic acid copolymer is a copolymer of ethylene and methacrylic acid.

[0044] The secondary unsaturated carboxylic acids can be used alone or in combination of two or more kinds.

[0045] The content ratio of the second unsaturated carboxylic acid relative to the second monomer component is lower than the content ratio of the first unsaturated carboxylic acid relative to the first monomer component.

[0046] Specifically, the content of the second unsaturated carboxylic acid is more than 0% by mass, preferably 5% by mass or more, more preferably 8% by mass or more, based on the second monomer component, from the viewpoints of dispersion stability and coating drying properties, and is less than 12% by mass, preferably 11% by mass or less, from the viewpoints of dispersion stability and coating drying properties.

[0047] The second monomer component may contain the above-mentioned other monomers as needed. As the other monomers, preferably, isobutyl (meth)acrylate is used. As the other monomers, more preferably, isobutyl acrylate is used.

[0048] The other monomers can be used alone or in combination of two or more kinds.

[0049] The content of the other monomer relative to the second monomer component is, for example, 15% by mass or less, preferably 10% by mass or less, and more preferably 0% by mass. That is, more preferably, the second monomer component does not contain any other monomer.

[0050] The polymerization method for the second monomer component is the same as the polymerization method for the first monomer component.

[0051] This results in a second ethylene-unsaturated carboxylic acid copolymer.

[0052] The second ethylene-unsaturated carboxylic acid copolymer has a weight average molecular weight of, for example, 8,000 to 150,000, or preferably 10,000 to 100,000, in terms of standard polystyrene measured by gel permeation chromatography (GPC).

[0053] The second ethylene-unsaturated carboxylic acid copolymer may be used alone or in combination of two or more kinds.

[0054] The content ratio of the second ethylene-unsaturated carboxylic acid copolymer relative to 100 parts by mass of the total amount of the first ethylene-unsaturated carboxylic acid copolymer and the second ethylene-unsaturated carboxylic acid copolymer is, for example, 20 parts by mass to 80 parts by mass, preferably 30 parts by mass to 70 parts by mass, and more preferably 40 parts by mass to 60 parts by mass.

[0055] The content of the second ethylene-unsaturated carboxylic acid copolymer relative to the first resin particles is, for example, 20% by mass to 80% by mass, preferably 30% by mass to 70% by mass, and more preferably 40% by mass to 60% by mass.

[0056] (Another first ethylene-unsaturated carboxylic acid copolymer) The first resin particles may also contain other first ethylene-unsaturated carboxylic acid copolymers.

[0057] Other examples of the first ethylene-unsaturated carboxylic acid copolymer include ethylene-unsaturated carboxylic acid copolymers having a higher content of unsaturated carboxylic acid than the second ethylene-unsaturated carboxylic acid copolymer.

[0058] The other first ethylene-unsaturated carboxylic acid copolymers can be used alone or in combination of two or more kinds.

[0059] The content of the other first ethylene-unsaturated carboxylic acid copolymer relative to the first resin particles is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0% by mass. That is, particularly preferably, the first resin particles do not contain other first ethylene-unsaturated carboxylic acid copolymers and are composed of the first ethylene-unsaturated carboxylic acid copolymer and the second ethylene-unsaturated carboxylic acid copolymer.

[0060] [Production of first resin particles] Examples of methods for producing the first resin particles include a melt-kneading method and an extrusion phase inversion method.Preferably, the melt-kneading method is used as the method for producing the first resin particles.

[0061] In the melt-kneading method, the first ethylene-unsaturated carboxylic acid copolymer, the second ethylene-unsaturated carboxylic acid copolymer, and other first ethylene-unsaturated carboxylic acid copolymers that are blended as necessary are melt-kneaded using a known kneading device.

[0062] In the melt-kneading, the melting temperature is, for example, 100°C to 250°C, or preferably 120°C to 200°C.

[0063] This produces the first resin that will form the first resin particles.The first resin is then dispersed in water to produce a dispersion of the first resin particles.

[0064] In addition, additives may be added to the dispersion of the first resin particles to improve production stability. Examples of additives include pH adjusters, sequestering agents (e.g., ethylenediaminetetraacetic acid and its salts), and lubricants (e.g., N-oleyl palmitamide, ethylenebisoleamide, and N-stearyl erucamide). The proportion of the additives added is determined appropriately depending on the purpose and application.

[0065] In addition, the carboxy groups of the first resin particles (specifically, the carboxy groups of the first ethylene-unsaturated carboxylic acid copolymer, the carboxy groups of the second ethylene-unsaturated carboxylic acid copolymer, and the carboxy groups of other first ethylene-unsaturated carboxylic acid copolymers) are neutralized with the first neutralizing agent and the second neutralizing agent.

[0066] The first neutralizing agent is an alkali metal compound. Examples of alkali metal compounds include alkali metal hydroxides. Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. Preferred alkali metal hydroxides include sodium hydroxide and potassium hydroxide. More preferred alkali metal hydroxides include sodium hydroxide.

[0067] The first neutralizing agent can be used alone or in combination of two or more kinds.

[0068] The second neutralizing agent is a basic nitrogen-containing compound. Examples of the basic nitrogen-containing compound include ammonia and amines. Examples of the amine include methylamine, triethylamine, triethanolamine, diethylamine, and dimethylethanolamine. A preferred example of the amine is methylamine.

[0069] The second neutralizing agent can be used alone or in combination of two or more kinds. Preferably, ammonia or an amine is used alone. More preferably, ammonia is used alone.

[0070] The first degree of neutralization of the first resin particles with the first neutralizing agent is 5 mol% to 60 mol%, preferably 10 mol% to 57 mol%, more preferably 20 mol% to 55 mol%, even more preferably 25 mol% to 53 mol%, particularly preferably 30 mol% to 52 mol%, most preferably 35 mol% to 50 mol%, or even 40 mol% to 48 mol%.

[0071] Specifically, the first degree of neutralization is 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 25 mol% or more, particularly preferably 30 mol% or more, most preferably 35 mol% or more, or even 40 mol% or more, and is 60 mol% or less, preferably 57 mol% or less, more preferably 55 mol% or less, even more preferably 53 mol% or less, particularly preferably 52 mol% or less, most preferably 50 mol% or less, or even 48 mol% or less.

[0072] If the first degree of neutralization is equal to or greater than the above lower limit, the dispersion stability can be improved.

[0073] On the other hand, if the first degree of neutralization is less than the lower limit, the dispersion stability decreases.

[0074] Furthermore, if the first degree of neutralization is equal to or less than the above upper limit, a dispersion of the first resin particles can be produced with a suitable viscosity.

[0075] On the other hand, if the first degree of neutralization exceeds the upper limit, it may not be possible to produce a dispersion of the first resin particles with a suitable viscosity.

[0076] Furthermore, the second degree of neutralization of the first resin particles with the second neutralizing agent is 1% to 55%, preferably 1% to 40%, more preferably 1% to 30%, even more preferably 1% to 20%, particularly preferably 1% to 15%, most preferably 3% to 10%, even more preferably 4% to 9%, or even more preferably 6% to 8%.

[0077] Specifically, the second degree of neutralization is 1% or more, preferably 3% or more, more preferably 4% or more, even more preferably 6% or more, and 55% or less, preferably 40% or less, more preferably 30% or less, even more preferably 20% or less, particularly preferably 15% or less, most preferably 10% or less, even 9% or less, even 8% or less.

[0078] If the second degree of neutralization is equal to or greater than the above lower limit, the film-forming properties can be improved.

[0079] On the other hand, if the second degree of neutralization is less than the above lower limit, the film-forming properties will be reduced.

[0080] Furthermore, if the second degree of neutralization is equal to or less than the above upper limit, a dispersion of the first resin particles can be produced with a suitable viscosity.

[0081] On the other hand, if the second degree of neutralization exceeds the upper limit, it may not be possible to produce a dispersion of the first resin particles with a suitable viscosity.

[0082] Preferably, the first degree of neutralization is higher than the second degree of neutralization. Specifically, the ratio of the first degree of neutralization to the second degree of neutralization (first degree of neutralization / second degree of neutralization) is, for example, more than 1, preferably 3 or more, more preferably 6 or more, and for example, 20 or less, preferably 10 or less, more preferably 8 or less.

[0083] When the ratio of the first degree of neutralization to the second degree of neutralization is equal to or greater than the above lower limit and equal to or less than the above upper limit, film-forming properties and coating drying properties can be improved.

[0084] The first and second degrees of neutralization are calculated from the ratio of raw materials used. Specifically, the amount of carboxyl group (mol) is calculated from the weight of the resin used and the content of unsaturated carboxylic acid, and the amount of neutralizing agent (mol) is calculated from the weight and purity of the neutralizing agent used, and the latter is divided by the former to determine the degree of neutralization.

[0085] The mass ratio of the first neutralizing agent to the second neutralizing agent is 2-25, preferably 5-22, more preferably 8-20, even more preferably 10-18, and particularly preferably 14-16.

[0086] Specifically, the mass ratio of the first neutralizing agent to the second neutralizing agent (first neutralizing agent / second neutralizing agent) is 2 or more, preferably 5 or more, more preferably 8 or more, even more preferably 10 or more, particularly preferably 14 or more, and 20 or less, preferably 19 or less, more preferably 18 or less, even more preferably 17 or less, particularly preferably 16 or less.

[0087] When the mass ratio of the first neutralizing agent to the second neutralizing agent is equal to or greater than the above lower limit, dispersion stability can be improved.

[0088] On the other hand, if the mass ratio of the first neutralizing agent to the second neutralizing agent is less than the above lower limit, the dispersion stability decreases.

[0089] Furthermore, when the mass ratio of the first neutralizing agent to the second neutralizing agent is equal to or less than the above upper limit, a dispersion of the first resin particles can be produced with a suitable viscosity.

[0090] On the other hand, if the mass ratio of the first neutralizing agent to the second neutralizing agent exceeds the upper limit, it may not be possible to produce a dispersion of the first resin particles with a suitable viscosity.

[0091] After the neutralizing agents (first neutralizing agent and second neutralizing agent) are added, the first resin and water are kept at a predetermined temperature for a predetermined time and stirred.

[0092] The holding conditions are such that the holding temperature is, for example, 100° C. to 190° C., or preferably 110° C. to 180° C. The holding time is, for example, 30 minutes to 12 hours, or preferably 1 hour to 10 hours.

[0093] This neutralizes the carboxy groups of the first resin, and first resin particles (a dispersion of first resin particles) are obtained that contain the first ethylene-unsaturated carboxylic acid copolymer, the second ethylene-unsaturated carboxylic acid copolymer, and other first ethylene-unsaturated carboxylic acid copolymers that are blended as needed.

[0094] In the dispersion of the first resin particles, the solid content concentration of the first resin particles is, for example, 10% by mass to 60% by mass, preferably 20% by mass to 50% by mass, and more preferably 30% by mass to 40% by mass.

[0095] In the first resin particles, the content of structural units derived from unsaturated carboxylic acids (first unsaturated carboxylic acid and second unsaturated carboxylic acid) is 5% by mass to 18% by mass, preferably 7% by mass to 17% by mass, more preferably 10% by mass to 15% by mass, and even more preferably 12% by mass to 14% by mass.

[0096] Specifically, in the first resin particles, the content of structural units derived from unsaturated carboxylic acids (first unsaturated carboxylic acid and second unsaturated carboxylic acid) is 5% by mass or more, preferably 7% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more, and 18% by mass or less, preferably 17% by mass or less, more preferably 15% by mass or less, even more preferably 14% by mass or less.

[0097] When the content of the structural units derived from the unsaturated carboxylic acids (the first unsaturated carboxylic acid and the second unsaturated carboxylic acid) is equal to or greater than the above lower limit, a dispersion of the first resin particles can be reliably produced.

[0098] On the other hand, if the content of structural units derived from unsaturated carboxylic acids (first unsaturated carboxylic acid and second unsaturated carboxylic acid) is less than the lower limit, it may not be possible to reliably produce a dispersion of the first resin particles.

[0099] Furthermore, if the content of structural units derived from unsaturated carboxylic acids (first unsaturated carboxylic acid and second unsaturated carboxylic acid) is equal to or less than the above upper limit, blocking resistance can be improved.

[0100] On the other hand, if the content of structural units derived from unsaturated carboxylic acids (primary unsaturated carboxylic acid and secondary unsaturated carboxylic acid) exceeds the upper limit, blocking resistance decreases.

[0101] The content of the structural unit derived from the unsaturated carboxylic acid in the first resin particles can be calculated from the charged amount.

[0102] The volume average particle diameter (D50) of the first resin particles is preferably larger than the volume average particle diameter (D50) of the second resin particles described below, and is, for example, 0.2 μm to 2.0 μm, preferably 0.3 μm to 1.0 μm, more preferably 0.4 μm to 0.6 μm.

[0103] The volume average particle size can be measured using a particle size analyzer (the same applies hereinafter).

[0104] <Second resin particles> From the viewpoint of improving film-forming properties, the aqueous dispersion preferably contains second resin particles.

[0105] The second resin particles have a higher content of structural units derived from the unsaturated carboxylic acid (third unsaturated carboxylic acid) described below than the content of structural units derived from the unsaturated carboxylic acids (first unsaturated carboxylic acid and second unsaturated carboxylic acid) in the first resin particles.

[0106] The second resin particles include a third ethylene-unsaturated carboxylic acid copolymer.

[0107] The tertiary ethylene-unsaturated carboxylic acid copolymer is a polymer of a third monomer component comprising ethylene and a tertiary unsaturated carboxylic acid.

[0108] The ethylene content relative to the third monomer component is, for example, 70% by mass to 88% by mass, preferably 78% by mass to 87% by mass, and more preferably 80% by mass to 84% by mass.

[0109] Examples of the tertiary unsaturated carboxylic acid include unsaturated carboxylic acids similar to those of the first unsaturated carboxylic acid.Preferably, a monobasic acid is used as the tertiary unsaturated carboxylic acid.From the viewpoints of film-forming properties and coating drying properties, more preferably, the tertiary unsaturated carboxylic acid is acrylic acid or methacrylic acid, and even more preferably, acrylic acid.In other words, more preferably, the tertiary ethylene-unsaturated carboxylic acid copolymer is a copolymer of ethylene and acrylic acid.

[0110] The tertiary unsaturated carboxylic acids can be used alone or in combination of two or more kinds.

[0111] The content of the tertiary unsaturated carboxylic acid is 12% by mass to 30% by mass, preferably 13% by mass to 22% by mass, and more preferably 17% by mass to 21% by mass, relative to the third monomer component.

[0112] Specifically, the content of the tertiary unsaturated carboxylic acid is 12% by mass or more, preferably 13% by mass or more, more preferably 17% by mass or more, and 30% by mass or less, preferably 22% by mass or less, more preferably 21% by mass or less, relative to the third monomer component.

[0113] When the content of the tertiary unsaturated carboxylic acid is equal to or greater than the above lower limit and equal to or less than the above upper limit, film-forming properties and coating drying properties can be improved.

[0114] The third monomer component optionally contains the other monomers described above.

[0115] The content of the other monomer relative to the third monomer component is, for example, 15% by mass or less, preferably 10% by mass or less, and more preferably 0% by mass. That is, more preferably, the third monomer component does not contain any other monomer.

[0116] The polymerization of the third monomer component is carried out in the same manner as the polymerization of the first monomer component.

[0117] This results in a third ethylene-unsaturated carboxylic acid copolymer.

[0118] The third ethylene-unsaturated carboxylic acid copolymer has a weight average molecular weight of, for example, 8,000 to 150,000, or preferably 10,000 to 100,000, in terms of standard polystyrene, as measured by gel permeation chromatography (GPC).

[0119] The third ethylene-unsaturated carboxylic acid copolymer can be used alone or in combination of two or more kinds.

[0120] The content ratio of the third ethylene-unsaturated carboxylic acid copolymer relative to the second resin particles is, for example, 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0121] (Other second ethylene-unsaturated carboxylic acid copolymers) The second resin particles may also contain another second ethylene-unsaturated carboxylic acid copolymer.

[0122] Other examples of the second ethylene-unsaturated carboxylic acid copolymer include ethylene-unsaturated carboxylic acid copolymers having a higher content of unsaturated carboxylic acid than the third ethylene-unsaturated carboxylic acid copolymer.

[0123] The second ethylene-unsaturated carboxylic acid copolymer may be used alone or in combination of two or more kinds.

[0124] The content of the other second ethylene-unsaturated carboxylic acid copolymer relative to the second resin particles is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0% by mass. That is, particularly preferably, the second resin particles do not contain the other second ethylene-unsaturated carboxylic acid copolymer and are made of the third ethylene-unsaturated carboxylic acid copolymer.

[0125] [Production of second resin particles] The method for producing the second resin particles is the same as the method for producing the first resin particles, except that in the method for producing the first resin particles, instead of the first ethylene-unsaturated carboxylic acid copolymer, the second ethylene-unsaturated carboxylic acid copolymer, and the other second ethylene-unsaturated carboxylic acid copolymer that is optionally blended, a third ethylene-unsaturated carboxylic acid copolymer and the other second ethylene-unsaturated carboxylic acid copolymer that is optionally blended are used.

[0126] This produces the second resin that constitutes the second resin particles.The second resin is then dispersed in water to produce a dispersion of the second resin particles.

[0127] In order to improve production stability, the dispersion of the second resin particles may contain additives similar to those added to the dispersion of the first resin particles.

[0128] In addition, the carboxy groups of the second resin particles (specifically, the carboxy groups of the third ethylene-unsaturated carboxylic acid copolymer and the carboxy groups of the other second ethylene-unsaturated carboxylic acid copolymer) are neutralized with the first neutralizing agent and the second neutralizing agent.

[0129] The first neutralizing agent is preferably sodium hydroxide.

[0130] The second neutralizing agent is preferably ammonia.

[0131] The third degree of neutralization of the second resin particles with the first neutralizing agent is, for example, 5 mol% to 60 mol%, preferably 10 mol% to 57 mol%, more preferably 20 mol% to 55 mol%, even more preferably 25 mol% to 53 mol%, particularly preferably 30 mol% to 52 mol%, most preferably 35 mol% to 50 mol%, or even 40 mol% to 48 mol%.

[0132] Specifically, the third degree of neutralization is, for example, 5 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 25 mol% or more, particularly preferably 30 mol% or more, most preferably 35 mol% or more, or even 40 mol% or more, and, for example, 60 mol% or less, preferably 57 mol% or less, more preferably 55 mol% or less, even more preferably 53 mol% or less, particularly preferably 52 mol% or less, most preferably 50 mol% or less, or even 48 mol% or less.

[0133] If the third degree of neutralization is equal to or greater than the above lower limit, the dispersion stability can be improved.

[0134] Furthermore, if the third degree of neutralization is equal to or less than the above upper limit, a dispersion of the second resin particles can be reliably produced.

[0135] Furthermore, the fourth degree of neutralization of the second resin particles by the second neutralizing agent is, for example, 1% to 55%, preferably 1% to 40%, more preferably 1% to 30%, even more preferably 1% to 20%, particularly preferably 1% to 15%, most preferably 3% to 10%, even more preferably 4% to 9%, or even more preferably 6% to 8%.

[0136] Specifically, the fourth degree of neutralization is 1% or more, preferably 3% or more, more preferably 4% or more, even more preferably 6% or more, and 55% or less, preferably 40% or less, more preferably 30% or less, even more preferably 20% or less, particularly preferably 15% or less, most preferably 10% or less, even 9% or less, even 8% or less.

[0137] When the fourth degree of neutralization is equal to or greater than the above lower limit, the film-forming properties can be improved.

[0138] Furthermore, if the fourth degree of neutralization is equal to or less than the above upper limit, a dispersion of the second resin particles can be reliably produced.

[0139] Preferably, the first degree of neutralization is higher than the second degree of neutralization. Specifically, the ratio of the first degree of neutralization to the second degree of neutralization (first degree of neutralization / second degree of neutralization) is, for example, more than 1, preferably 3 or more, more preferably 6 or more, even more preferably 1 or more, and for example, 20 or less, preferably 10 or less, more preferably 8 or less.

[0140] When the ratio of the first degree of neutralization to the second degree of neutralization is equal to or greater than the above lower limit and equal to or less than the above upper limit, film-forming properties and coating drying properties can be improved.

[0141] The mass ratio of the first neutralizing agent to the second neutralizing agent is, for example, 2-25, preferably 5-22, more preferably 8-20, still more preferably 10-18, and particularly preferably 14-16.

[0142] Specifically, the mass ratio of the first neutralizing agent to the second neutralizing agent (first neutralizing agent / second neutralizing agent) is, for example, 2 or more, preferably 5 or more, more preferably 8 or more, even more preferably 10 or more, particularly preferably 14 or more, and for example, 25 or less, preferably 22 or less, more preferably 20 or less, even more preferably 18 or less, particularly preferably 16 or less.

[0143] When the mass ratio of the first neutralizing agent to the second neutralizing agent is equal to or greater than the above lower limit, the coating drying properties can be improved.

[0144] Furthermore, if the mass ratio of the first neutralizing agent to the second neutralizing agent is equal to or less than the above upper limit, a dispersion of the second resin particles can be produced with a suitable viscosity.

[0145] After the neutralizing agents (first neutralizing agent and second neutralizing agent) are added, the second resin and water are kept at a predetermined temperature for a predetermined time and stirred.

[0146] The holding conditions for the second resin are the same as those for the first resin.

[0147] This neutralizes the carboxy groups of the second resin, yielding second resin particles (a dispersion of second resin particles) containing the third ethylene-unsaturated carboxylic acid copolymer and, if necessary, other second ethylene-unsaturated carboxylic acid copolymers.

[0148] In the dispersion of the second resin particles, the solid content concentration of the second resin particles is, for example, 10% by mass to 60% by mass, preferably 20% by mass to 50% by mass, and more preferably 30% by mass to 40% by mass.

[0149] The content of structural units derived from unsaturated carboxylic acids (tertiary unsaturated carboxylic acids) in the second resin particles is higher than the content of structural units derived from unsaturated carboxylic acids (first unsaturated carboxylic acids and second unsaturated carboxylic acids) in the first resin particles. Specifically, the content of structural units derived from unsaturated carboxylic acids (tertiary unsaturated carboxylic acids) in the second resin particles is, for example, 12% to 30% by mass, preferably 15% to 25% by mass, and more preferably 18% to 22% by mass.

[0150] Specifically, the content of structural units derived from unsaturated carboxylic acids (third unsaturated carboxylic acids) in the second resin particles is, for example, 12% by mass or more, preferably 15% by mass or more, more preferably 18% by mass or more, and for example, 30% by mass or less, preferably 25% by mass or less, more preferably 22% by mass or less.

[0151] When the content of the structural unit derived from the unsaturated carboxylic acid (tertiary unsaturated carboxylic acid) is equal to or greater than the above lower limit, a dispersion of the second resin particles can be reliably produced.

[0152] Furthermore, if the content of structural units derived from unsaturated carboxylic acids (tertiary unsaturated carboxylic acids) is equal to or less than the above upper limit, water resistance can be improved.

[0153] The content of the structural unit derived from the unsaturated carboxylic acid in the second resin particles can be calculated from the charged amount.

[0154] The volume average particle diameter (D50) of the second resin particles is preferably smaller than the volume average particle diameter (D50) of the first resin particles, and is, for example, 0.01 μm to 2.0 μm, or preferably 0.02 μm to 1.0 μm.

[0155] If the volume average particle diameter of the second resin particles is smaller than that of the first resin particles, the second resin particles can enter the gaps between the first resin particles during film formation (when forming a resin layer, described below), improving film-forming properties and, as a result, water resistance.

[0156] [Method for producing aqueous dispersion] The aqueous dispersion is produced by blending the first resin particles, the optionally blended second resin particles, and the optionally blended additives. Specifically, the aqueous dispersion is produced by blending a dispersion of the first resin particles (the first resin particles and water), the optionally blended second resin particles (the second resin particles and water), and the optionally blended additives.

[0157] Examples of additives include curing agents, crosslinking agents, film-forming aids, antifoaming agents, tackifiers, hardness-imparting agents, preservatives, thickeners, antifreeze agents, dispersants, inorganic pigments, and organic pigments. The additives are blended in appropriate ratios. The additives can be used alone or in combination of two or more types.

[0158] This gives an aqueous dispersion.

[0159] When the aqueous dispersion contains the second resin particles, the content of the second resin particles is, for example, 5 to 20 parts by mass relative to 100 parts by mass of the total amount of the first resin particles and the second resin particles.

[0160] If the content of the second resin particles is within the above range, the water resistance can be improved.

[0161] When the aqueous dispersion contains the second resin particles, the content of the first resin particles is, for example, 80 parts by mass to 95 parts by mass.

[0162] The viscosity (25°C) of the aqueous dispersion is, for example, 100 mPa·s to 900 mPa·s, preferably 200 mPa·s to 800 mPa·s, more preferably 300 mPa·s to 700 mPa·s, still more preferably 400 mPa·s to 650 mPa·s, and particularly preferably 500 mPa·s to 600 mPa·s.

[0163] The viscosity can be measured, for example, by a Brookfield viscometer.

[0164] The solid content concentration of the aqueous dispersion is, for example, 10% by mass to 60% by mass, preferably 20% by mass to 50% by mass, and more preferably 30% by mass to 40% by mass.

[0165] The melt flow rate (MFR) (190°C) of the resin components (first resin particles and optionally blended second resin particles) is, for example, 1 g / 10 min to 70 g / 10 min, preferably 2 g / 10 min to 15 g / 10 min, and more preferably 3 g / 10 min to 7 g / 10 min.

[0166] The melt flow rate can be measured in accordance with ASTM D1238-65T under conditions of 190°C and a load of 2.16 kg.

[0167] This aqueous dispersion can be suitably used for a substrate, particularly as a coating layer for imparting water resistance, and also as an adhesive for bonding substrates together.

[0168] <Laminate> Referring to FIG. 1, one embodiment of the laminate 10 will be described in detail.

[0169] In Figure 1, the up-down direction of the paper surface is the up-down direction (thickness direction), and the upper side of the paper surface is the upper side (one side in the thickness direction), and the lower side of the paper surface is the lower side (the other side in the thickness direction). Also, the left-right direction and the depth direction of the paper surface are surface directions perpendicular to the up-down direction. Specifically, they conform to the directional arrows in each figure.

[0170] As shown in FIG. 1, the laminate 10 includes a first base material 1 as a base material and a resin layer 2 in this order toward one side in the thickness direction.

[0171] [First base material] The first base material 1 has a film shape and is disposed on the entire lower surface of the resin layer 2 so as to be in contact with the lower surface of the resin layer 2.

[0172] The first substrate 1 is not particularly limited. Examples of the first substrate 1 include resin films, metal films, and paper. Examples of materials for the resin films include polymeric materials. Examples of polymeric materials include olefin resins (e.g., polyethylene and polypropylene), acrylic resins, polyester resins, polycarbonate resins, acrylonitrile-styrene-butadiene copolymer resins (ABS resins), polyamide resins (e.g., nylon), and polyphenylene sulfide resins. Examples of materials for the metal films include aluminum, gold, silver, copper, nickel, zinc, titanium, cobalt, indium, and chromium. Examples of materials for the paper include cellulose.

[0173] The first substrate 1 may be subjected to a surface treatment as needed, such as ink (solvent-based or water-based) coating, plating, coupling, and vacuum plasma treatment.

[0174] There are no particular limitations on the thickness of the first substrate 1. The thickness of the first substrate 1 is, for example, 10 μm to 100 μm.

[0175] [Resin layer] The resin layer 2 is a dried product of an aqueous dispersion.

[0176] The resin layer 2 has a thickness of, for example, 0.1 μm to 10 μm.

[0177] [Method of manufacturing laminate] An embodiment of a method for manufacturing the laminate 10 will be described in detail with reference to FIGS. 2A and 2B.

[0178] The method for manufacturing the laminate 10 includes a first step of preparing a first substrate 1, and a second step of arranging a resin layer 2 on one surface of the first substrate 1 in the thickness direction.

[0179] [1st step] In the first step, a first substrate 1 is prepared as shown in FIG. 2A.

[0180] [Second process] In the second step, as shown in FIG. 2B, a resin layer 2 is disposed on one surface of the first substrate 1 in the thickness direction.

[0181] To dispose the resin layer 2 on one surface of the first substrate 1 in the thickness direction, the above-mentioned aqueous dispersion is applied to one surface of the first substrate 1 in the thickness direction, and then dried.

[0182] Examples of the coating method include known coating methods such as bar coating, curtain coating, roll coating, and blade coating.

[0183] The drying temperature is, for example, 50 to 160° C., or preferably 70 to 140° C. The drying time is, for example, 10 to 120 seconds.

[0184] As a result, the resin layer 2, which is a dried product of the water dispersion, is disposed on one surface of the first substrate 1 in the thickness direction.

[0185] In this way, the laminate 10 is manufactured.

[0186] The laminate 10 includes a resin layer 2 that is a dried product of the above-mentioned aqueous dispersion, which can improve water resistance and blocking resistance.

[0187] Next, a method for bonding the substrates together (the first substrate 1 and the second substrate 3 together) using the laminate 10 will be described in detail.

[0188] In this method, as shown in FIG. 2C, the second base material 3 is placed on one surface in the thickness direction of the resin layer 2, and the first base material 1 and the second base material 3 are bonded together by thermocompression bonding (heat sealing).

[0189] There is no particular limitation on the second substrate 3. As the second substrate 3, a substrate similar to the first substrate 1 described above is selected.

[0190] The first substrate 1 and the second substrate 3 may be the same or different from each other. Preferably, the first substrate 1 and the second substrate 3 are different from each other, and more preferably, the first substrate 1 is paper and the second substrate 3 is a metal film (e.g., an aluminum film).

[0191] As conditions for thermocompression bonding, the temperature for thermocompression bonding is, for example, 80° C. to 190° C., preferably 100° C. to 170° C. The pressure for thermocompression bonding is, for example, 1.5 kg / cm 3 ~3.5kg / cm 3 is.

[0192] In this way, the first substrate 1 and the second substrate 3 are bonded together to produce a laminate 10 having the first substrate 1, the resin layer 2, and the second substrate 3 in this order toward one side in the thickness direction.

[0193] In the above description, in the laminate 10, the resin layer 2 is disposed on one surface in the thickness direction of the first substrate 1, but the resin layer 2 may be disposed on one surface and the other surface in the thickness direction of the first substrate 1. In such a case, the second substrate 3 can be disposed on one surface and the other surface in the thickness direction of the resin layer 2.

[0194] In the above description, a resin layer 2 is placed on the first substrate 1, and the first substrate 1 and the second substrate 3 are bonded together via the resin layer 2. However, as shown in FIG. 3A, a resin layer 2 can be placed on each of the first substrate 1 and the second substrate 3, and then the first substrate 1 and the second substrate 3 can be bonded together via the resin layer 2 as shown in FIG. 3B.

[0195] Furthermore, a resin layer 2 is disposed on the first substrate 1 to produce a laminate 10. Then, the laminate 10 can be folded so that the resin layers 2 face each other, and the first substrates 1 can be bonded together. In this way, a bag can be produced. The laminate 10 used to produce a bag is a bag material.

[0196] <Action and effect> In the aqueous dispersion, the first resin particles contain a first ethylene-unsaturated carboxylic acid copolymer and a second ethylene-unsaturated carboxylic acid copolymer, each of which has a different content of unsaturated carboxylic acid. The first resin particles contain structural units derived from unsaturated carboxylic acid in an amount of 5% by mass or more and 18% by mass or less.

[0197] The carboxy groups of the first resin particles are neutralized to a predetermined degree of neutralization by a first neutralizing agent (alkali metal compound) and a second neutralizing agent (basic nitrogen-containing compound).

[0198] Therefore, film-forming properties and coating drying properties can be improved.

[0199] Specifically, the first resin particles contain a first ethylene-unsaturated carboxylic acid copolymer and a second ethylene-unsaturated carboxylic acid copolymer, each of which has a different content of unsaturated carboxylic acid. As a result, the former, which has a higher content of unsaturated carboxylic acid, acts as a hydrophilic component to improve the dispersion stability of the first resin particles, while the latter, which has a lower content of unsaturated carboxylic acid, acts as a crystalline component to improve the blocking resistance of a coating and drying product of the dispersion of the first resin particles.

[0200] The carboxy groups of the first resin particles are neutralized with two types of neutralizing agents: a first neutralizing agent (alkali metal compound) and a second neutralizing agent (basic nitrogen-containing compound).

[0201] In particular, neutralization with the second neutralizing agent (basic nitrogen-containing compound) can further swell the first resin particles, thereby improving film-forming properties and, as a result, water resistance.

[0202] The first resin particles contain structural units derived from unsaturated carboxylic acid in an amount of 5% by mass to 18% by mass, which ensures the dispersion stability of the first resin particles by containing a certain amount of unsaturated carboxylic acid, and ensures the water resistance of the coated and dried dispersion of the first resin particles by not containing an excessive amount of unsaturated carboxylic acid.

[0203] <Modification> In the modified example, the same components and steps as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, the modified example can achieve the same effects as those in the first embodiment unless otherwise specified. Furthermore, the first embodiment and its modified example can be combined as appropriate.

[0204] In the above description, the first resin particles and the second resin particles are neutralized separately, but the first resin particles and the second resin particles can also be neutralized together. [Example]

[0205] Specific numerical values ​​of blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(numeric values ​​defined as "not more than" or "less than") or lower limit values ​​(numeric values ​​defined as "not less than" or "exceeding") of blending ratios (content ratios), physical property values, parameters, etc. described in the above "Description of the Invention." Furthermore, unless otherwise specified in the following description, "parts" and "%" are based on mass.

[0206] <Ingredient details> Details of the ethylene-unsaturated carboxylic acid copolymer are shown in Table 1.

[0207] <Production of aqueous dispersion> Examples 1, 2, 4, Comparative Examples 1 to 3, and Comparative Examples 5 to 8 According to the formulations shown in Tables 2 and 3, a first ethylene-unsaturated carboxylic acid copolymer and a second ethylene-unsaturated carboxylic acid copolymer were melt-kneaded. This gave a first resin. Next, the first resin, water, a first neutralizing agent, and a second neutralizing agent were mixed, and the mixture was heated to 170°C while stirring and maintained for 4 hours, and then cooled to room temperature. This neutralized the carboxy groups of the first resin. As a result, an aqueous dispersion containing first resin particles was obtained. Note that in Comparative Examples 3 to 5, a dispersion of first resin particles was not obtained. Note that in Tables 2 and 3, the values ​​for the resin and neutralizing agent are relative values, and the values ​​for water are absolute values. The total amount of raw materials charged was 1,000 g.

[0208] Example 4, Example 5 and Comparative Example 4 The first ethylene-unsaturated carboxylic acid copolymer and the second ethylene-unsaturated carboxylic acid copolymer were melt-kneaded according to the formulations shown in Tables 2 and 3. This gave a first resin.

[0209] Next, the first resin, the second resin, water, the first neutralizer, and the second neutralizer were mixed and stirred. The mixture was heated to 170°C and held for 4 hours, then cooled to room temperature. This neutralized the carboxy groups of the first resin and the second resin. This resulted in an aqueous dispersion containing the first resin particles and the second resin particles. The total amount of raw materials charged was 1,000 g.

[0210] Example 3 According to the formulations listed in Table 2, the first ethylene-unsaturated carboxylic acid copolymer and the second ethylene-unsaturated carboxylic acid copolymer were fed at a rate of 50 g / min from the hopper of a twin-screw extruder (Ikegai Iron Works, PCM-30, L / D=40). A 3.5% aqueous solution of potassium hydroxide was continuously fed at a rate of 28 g / min from a feed port provided at the vent of the extruder, and the mixture was continuously extruded at a heating temperature of 110°C. The extruded resin mixture was then cooled to 90°C in a jacketed static mixer attached to the extruder port and then poured into 80°C warm water. This yielded an aqueous dispersion. The total amount of raw materials charged was 1,000 g.

[0211] <Production of laminate> In the first step, a cup base paper (200 g / m 2 (manufactured by Tokyo Paper Co., Ltd.) was prepared.

[0212] In the second step, a resin layer was disposed on one surface of the first substrate in the thickness direction. Specifically, the aqueous dispersions of the examples and comparative examples were applied to one surface of the first substrate in the thickness direction in a coating amount of 6 g / m. 2 The resin layer was applied twice with a wire bar so that the thickness of the resin layer became 100 μm, and each application was dried at 130° C. for 15 seconds. This resulted in a resin layer being disposed on one surface of the first substrate in the thickness direction. This produced a first laminate for testing.

[0213] In the third step, an aluminum foil as a second substrate was placed on one surface of the resin layer in the thickness direction, and the resin layer was heated at 110°C under a pressure of 1 kg / cm. 2 The laminate was then heat sealed at 100° C. for 0.5 seconds, thereby producing a second laminate for testing. <Evaluation> [Neutralization level] The degree of neutralization of each example and comparative example was calculated based on the amount of each compound charged, and the results are shown in Tables 2 and 3.

[0214] [Volume average particle size (D50)] The volume average particle diameters of the first resin particles and the second resin particles in each example and each comparative example are as follows: Measurements were performed using particle size analyzers (Microtrac MT3300EXII and Nanotrac Wave II-EX150 manufactured by Microtrac Bell Co., Ltd.) The results are shown in Tables 2 and 3.

[0215] [viscosity] The viscosity of the aqueous dispersions of each Example and Comparative Example was measured at 25° C. using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) The results are shown in Tables 2 and 3.

[0216] [Melt flow rate] The melt flow rate of the resin components (first resin particles and second resin particles) of each Example and Comparative Example was measured at 190°C under a load of 2.16 kg in accordance with ASTM D1238-65T. The results are shown in Tables 2 and 3.

[0217] [water resistance] {Cobb value} The amount of water absorbed after 300 seconds was measured for the first test laminate of each Example and Comparative Example by the Cobb method (JIS P8140). The results are shown in Tables 2 and 3.

[0218] [Oil resistance] {Kit value} For the first test laminate of each example and each comparative example, the Kit value was measured using the kit number test liquid (oil) based on JAPAN TAPPI No. 41. The results are shown in Tables 2 and 3.

[0219] [Heat sealability] The heat sealability of the second test laminates of each Example and Comparative Example was evaluated based on the following criteria. The results are shown in Tables 2 and 3. {standard} A: Adhesion between the first and second substrates was confirmed. B: Adhesion between the first substrate and the second substrate could not be confirmed.

[0220] [Hot peel strength] The 90° peel strength (N / 15 mm) of the second test laminate of each example and each comparative example was measured at a pulling speed of 200 mm / min. The results are shown in Tables 2 and 3.

[0221] [Blocking] The resin layers in the first test laminates of each example and each comparative example were laminated together and subjected to a pressure of 0.5 kg / cm 2 The specimen was compressed at 100°C for 4 seconds, and the temperature at which it could be peeled off without resistance was measured. The blocking properties were evaluated based on the following criteria. The results are shown in Tables 2 and 3. {standard} A: Peeling was possible at 45°C. B: There was resistance at 45°C, but peeling was possible at 40°C. C: There was resistance at 40°C, but peeling was possible at 30°C.

[0222] [Odor] The odor of the aqueous dispersions of each Example and Comparative Example was evaluated by a sensory test at 25° C. The results are shown in Tables 2 and 3. {standard} A: I didn't notice any irritating odor. B: A weak pungent odor was detected. C: A strong pungent odor was felt

[0223] [Table 1]

[0224] [Table 2]

[0225] [Table 3] [Explanation of symbols]

[0226] 1 Base material 2 Resin layer 10 Laminate

Claims

1. Contains first resin particles and water, the first resin particles include a first ethylene-unsaturated carboxylic acid copolymer and a second ethylene-unsaturated carboxylic acid copolymer; the first ethylene-unsaturated carboxylic acid copolymer is a polymer of a first monomer component including ethylene and a first unsaturated carboxylic acid; a content ratio of the first unsaturated carboxylic acid relative to the first monomer component is 12% by mass or more and 30% by mass or less, the second ethylene-unsaturated carboxylic acid copolymer is a polymer of a second monomer component including ethylene and a second unsaturated carboxylic acid; the content of the second unsaturated carboxylic acid is more than 0% by mass and less than 12% by mass with respect to the second monomer component, the first resin particles have a content of structural units derived from an unsaturated carboxylic acid of 5% by mass or more and 18% by mass or less; carboxy groups of the first resin particles are neutralized with a first neutralizing agent and a second neutralizing agent; the first neutralizing agent is an alkali metal compound; the second neutralizing agent is a basic nitrogen-containing compound, a first degree of neutralization of the first resin particles with the first neutralizing agent is 5 mol % or more and 60 mol % or less; a second degree of neutralization of the first resin particles with the second neutralizing agent is 1 mol % or more and 55 mol % or less; The aqueous dispersion, wherein the mass ratio of the first neutralizing agent to the second neutralizing agent is 2 or more and 25 or less.

2. Further, the second resin particles are contained, the second resin particles include a third ethylene-unsaturated carboxylic acid copolymer; the second resin particles have a content of structural units derived from an unsaturated carboxylic acid of 12% by mass or more and 30% by mass or less; a content ratio of structural units derived from an unsaturated carboxylic acid in the second resin particles is higher than a content ratio of structural units derived from an unsaturated carboxylic acid in the first resin particles; carboxy groups of the second resin particles are neutralized with the first neutralizing agent and the second neutralizing agent; a third degree of neutralization of the second resin particles with the first neutralizing agent is 5 mol % or more and 60 mol % or less; a fourth degree of neutralization of the second resin particles with the second neutralizing agent is 1 mol % or more and 55 mol % or less; The mass ratio of the first neutralizing agent to the second neutralizing agent is 2 or more and 25 or less, The aqueous dispersion according to claim 1 , wherein a content ratio of the second resin particles is 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the total amount of the first resin particles and the second resin particles.

3. The aqueous dispersion according to claim 1 , wherein the second degree of neutralization is 1% or more and 15% or less.

4. A substrate and a resin layer are provided in this order toward one side in a thickness direction, A laminate, wherein the resin layer is a dried product of the aqueous dispersion according to any one of claims 1 to 3.

Images