Neoprene latex composition

Abstract

One embodiment of the present invention relates to a chloroprene latex composition and a method for manufacturing an adhesive article, the chloroprene latex composition comprising: a chloroprene latex (A) containing a chloroprene-based polymer satisfying requirement (a-1), and a tackifier (B) having a softening point of 85°C to 155°C as determined by the ring and ball method. (a-1): The percentage of tetrahydrofuran-insoluble component α [mass%] in 100% by mass of the chloroprene-based polymer and the enthalpy of dissolution β [mJ / mg] of the chloroprene-based polymer as determined by differential scanning calorimetry (DSC) satisfy the following formula.

Description

Technical Field

[0001] One embodiment of the present invention relates to a chloroprene latex composition. Background Technology

[0002] Chloroprene latex is a latex containing chloroprene polymer. Chloroprene polymer is a polychloroprene obtained by emulsification polymerization of 2-chloro-1,3-butadiene (hereinafter also referred to as "chloroprene"), exhibiting high cohesiveness and crystallinity. Chloroprene polymer is mainly manufactured through emulsification polymerization. Chloroprene latex, containing polymer particles dispersed in water, can be applied to a substrate without dissolving the chloroprene polymer in a solvent, and is known to be an environmentally friendly water-based adhesive (Non-Patent Literature 1). Water-based adhesives using chloroprene latex are used in applications such as furniture, footwear, civil engineering, and diving suits.

[0003] In recent years, due to global regulations on volatile organic compounds (VOCs), there has been a growing demand for water-based adhesives for chloroprene latex, replacing solvent-based adhesives with water-based adhesives which have a lower environmental impact. Various water-based adhesives have been developed. For example, Patent Document 1 discloses a water-based adhesive characterized by containing polychloroprene latex obtained by emulsification polymerization in the presence of acetylated polyvinyl alcohol and zinc oxide.

[0004] Here, chloroprene-based adhesives are mostly used as contact adhesives, and aqueous adhesives for chloroprene latex are also used as contact adhesives. Bonding using contact adhesives involves drying the adhesive applied to the bonding surfaces of the adherends to form an adhesive layer, then bonding the adhesive layers together to exhibit adhesion.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-176999

[0008] Non-patent literature

[0009] Non-Patent Literature 1: "Improvement of Chloroprene-Based Adhesives", Kenjiro Gota, Journal of the Japan Rubber Industry Association, Vol. 52, No. 3, March 1979, pp. 167-178 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] When using an aqueous adhesive based on chloroprene latex as a contact adhesive, as described in Non-Patent Document 1, the drying time of the water in the chloroprene latex dispersion medium is time-consuming, thus resulting in a longer adhesive layer formation time. Consequently, compared to solvent-based adhesives, there is a problem of longer bonding time. Furthermore, when bonding occurs with insufficiently dried adhesive layers and residual water in the adhesive layers, the initial adhesive strength is insufficient, causing the adhesive layers to easily peel off. Additionally, the normal adhesive strength of the bonded product after curing can be improved, and there is also a problem of easy peeling at high temperatures (above 60°C).

[0012] When the adhesive composition described in Patent Document 1 is used as a contact adhesive, if the water in the latex dispersion medium is not sufficiently dried, the initial adhesive strength, normal adhesive strength, and heat resistance will all be insufficient. In other words, if the adhesive composition described in Patent Document 1 is not dried to the point where the adhesive layer is completely dry, the initial adhesive strength, normal adhesive strength, and heat resistance will be insufficient, and it will be unable to fully perform its function as a contact adhesive.

[0013] One embodiment of the present invention provides a chloroprene latex composition that, even when used as a contact adhesive with a residual dispersion medium in the adhesive layer (i.e., a layer containing the solid components of the chloroprene latex composition), exhibits superior initial adhesion, normal adhesion, and heat resistance compared to conventional aqueous contact adhesives.

[0014] Methods for solving problems

[0015] Through research, the inventors discovered that the aforementioned problem can be solved by the following configuration example. The configuration example of this invention is as follows.

[0016] In addition, in this specification, "A~B" which indicates a numerical range means above A and below B.

[0017] [1] A chloroprene latex composition (X) comprising:

[0018] Chloroprene latex (A) containing a chloroprene-based polymer that satisfies the following requirement (a-1), and

[0019] Tackifier (B) with a softening point of 85℃~155℃ as determined by the ring and ball method (according to the test method of JIS K 5902),

[0020] (a-1) The percentage of tetrahydrofuran-insoluble component α [mass%] in 100% mass of chloroprene polymers and the enthalpy of dissolution β [mJ / mg] of chloroprene polymers determined by differential scanning calorimetry (DSC) satisfy the following equation (1).

[0021] .

[0022] [2] The chloroprene latex composition (X) of [1], wherein the chloroprene latex (A) comprises:

[0023] First chloroprene latex containing 0-15% by mass of tetrahydrofuran-insoluble components and having a solubility enthalpy of 10-40 [mJ / mg] of chloroprene-based polymers, and

[0024] Second chloroprene latex containing 70-98% by mass of tetrahydrofuran-insoluble components and having a solubility enthalpy of 0-10 [mJ / mg] of chloroprene polymers.

[0025] [3] In the chloroprene latex composition (X) of [2], the solid content of the chloroprene latex (A) is 1 to 99% by mass of the first chloroprene latex and 99 to 1% by mass of the second chloroprene latex.

[0026] [4] A chloroprene latex composition (X) of any one of [1] to [3], wherein the chloroprene latex (A) comprises an anionic emulsifier.

[0027] [5] The chloroprene latex composition (X) of [4] is an anionic emulsifier of rosin acid salt.

[0028] [6] A chloroprene latex composition (X) of any one of [1] to [5], wherein the percentage of the tetrahydrofuran insoluble component α [mass%] and the enthalpy of dissolution β [mJ / mg] satisfy the following formula (2).

[0029] .

[0030] [7] The chloroprene latex composition (X) of any one of [1] to [6], wherein the tackifier (B) comprises a carboxyl-containing compound.

[0031] [8] Chloroprene latex composition (X) such as [7], wherein the tackifier (B) comprises a product of the reaction of an unsaturated carboxylic acid or anhydride with rosin.

[0032] [9] The chloroprene latex composition (X) of [8], wherein the unsaturated carboxylic acid or anhydride is selected from at least one of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride and cinnamic acid.

[0033]

[10] The chloroprene latex composition (X) of any one of [1] to [9] contains 3 to 90 parts by weight of the tackifier (B) relative to 100 parts by weight of the solids component of the chloroprene latex (A).

[0034]

[11] The amount of solid component of the chloroprene latex composition (X) of any one of [1] to

[10] is 40 to 70% by mass when the mass of the chloroprene latex composition (X) is set to 100% by mass.

[0035]

[12] A chloroprene latex composition (X) of any one of [1] to

[11] further comprising a pH adjuster (C).

[0036]

[13] The chloroprene latex composition (X) of

[12] , wherein the pH adjuster (C) is selected from at least one of amino acids, organic acids and inorganic weak acids.

[0037]

[14] The chloroprene latex composition (X) of

[12] or

[13] , wherein the pH adjuster (C) is at least one weak acid whose reciprocal logarithm (pKa) of the acid dissociation constant at 25°C falls in the range of 8.0 to 11.0.

[0038]

[15] The product of the amount of pH adjuster (C) used relative to 100 grams of the solid component of the chloroprene rubber (A) in the chloroprene latex composition (X) of any one of

[12] to

[14] is 0.1 to 30 mmol.

[0039]

[16] A method for manufacturing an adhesive article, comprising the following steps:

[0040] Step (1) of attaching the chloroprene latex composition (X) of any one of [1] to

[15] to at least a portion of each of the first and second substrates.

[0041] Step (2) involves drying the chloroprene latex composition (X) attached to the first bonded body and the chloroprene latex composition (X) attached to the second bonded body to form a layer containing the solid components of the chloroprene latex composition (X).

[0042] The process (3) of bonding the layer formed on the first bonded body to the layer formed on the second bonded body by mutual contact.

[0043] Invention Effects

[0044] An embodiment of the present invention provides a chloroprene latex composition that, even when used as a contact adhesive with a residual dispersion medium in the adhesive layer (i.e., a layer containing the solid components of the chloroprene latex composition), exhibits superior initial adhesion, normal adhesion, and heat resistance compared to conventional aqueous contact adhesives. Attached Figure Description

[0045] Figure 1 It is a graph showing the relationship between the Logβ value, calculated from the enthalpy of dissolution β (mJ / mg) of the chloroprene polymer in the chloroprene latex, and the percentage of the tetrahydrofuran insoluble component of the chloroprene polymer, and a graph of the straight line represented by Equation (1) on the graph.

[0046] Figure 2 This is an example diagram of a heat resistance test specimen suspended in an oven. Detailed Implementation

[0047] ≪Chloroprene Latex Composition (X)≫

[0048] The chloroprene latex composition (X) comprises a chloroprene latex (A) containing a chloroprene-based polymer that satisfies certain requirements, and a tackifier (B) having a softening point of 85°C to 155°C as determined by the ring and ball method (according to the determination method of JIS K 5902).

[0049] <Chloroprene Latex (A)>

[0050] Chloroprene latex (A) is a latex in which a chloroprene-based polymer satisfying the following requirement (a-1) is dispersed in a dispersion medium such as water. Examples of the dispersion medium include water and aqueous solvents containing water and water-soluble alcohols, but water is preferred.

[0051] [Chloroprene-based polymers]

[0052] The chloroprene polymer contained in chloroprene latex (A) satisfies the following requirement (a-1).

[0053] [Requirement (a-1)]

[0054] When the percentage of tetrahydrofuran-insoluble component in 100% by mass of the chloroprene polymer is set as α [mass%], and the enthalpy of melting (also called melting enthalpy) of the chloroprene polymer determined by differential scanning calorimetry (DSC) is set as β [mJ / mg], α and β satisfy the following formula (1), preferably further satisfying the following formula (1a), and more preferably also satisfying the following formula (1b).

[0055] .

[0056]

[0057]

[0058] Here, the tetrahydrofuran insoluble component percentage α [mass%] and the enthalpy of dissolution β [mJ / mg] were both determined by the methods described in the examples below. Furthermore, the tetrahydrofuran insoluble component percentage is the proportion of insoluble components contained in tetrahydrofuran at 25°C.

[0059] When the chloroprene polymer in the chloroprene latex (A) satisfies formula (1), the chloroprene latex composition (X) containing the chloroprene latex (A) tends to have excellent initial adhesion, normal adhesion, and heat resistance. Here, initial adhesion is the adhesion immediately after the layers containing solid components prepared by drying the chloroprene latex composition (X) are bonded together, or shortly after bonding (e.g., 5 minutes). In addition, normal adhesion is the adhesion when the layers containing solid components prepared by drying the chloroprene latex composition (X) are bonded together and cured for a long time (e.g., 24 hours). Initial adhesion can be, for example, the adhesion after 5 minutes when the layers containing solid components obtained by applying the chloroprene latex composition (X) to the substrate and drying it at 23°C and 50% relative humidity for 10 minutes are bonded together, specifically determined by the method described in the examples below. Normal adhesion can be, for example, the adhesion after bonding layers containing solid components together and curing them for 24 hours at 23°C and 50% relative humidity, specifically determined by the method described in the following examples.

[0060] Furthermore, the layer containing solid components prepared by drying the chloroprene latex composition (X) can be a layer of solid components that are entirely wetted by a dispersion medium such as water, a layer of solid components that are partially wetted, or a layer of solid components that are entirely dried. Additionally, the layer containing solid components can be in a state where part or all of the layer containing solid components is swollen by a dispersion medium.

[0061] The description in this specification is not intended to be bound by any particular theory, but the reason why the initial adhesive strength and normal adhesive strength of the chloroprene latex composition (X) when the chloroprene polymer satisfies formula (1) can be presumed to be based on the following (a1)~(a3).

[0062] (a1) The higher the tetrahydrofuran insoluble content of the chloroprene polymer, the easier it is to improve the initial adhesion and normal adhesion of the layer containing the solid component of the chloroprene polymer.

[0063] (a2) The higher the percentage of tetrahydrofuran-insoluble components in chloroprene polymers, the easier it is for the crystallinity of chloroprene polymers to decrease.

[0064] (a3) The higher the crystallinity of the chloroprene polymer, the easier it is to improve the initial adhesion and normal adhesion of the layer containing the solid component of the chloroprene polymer.

[0065] Furthermore, the higher the crystallinity, the greater the enthalpy of dissolution.

[0066] The chloroprene polymers that satisfy formula (1) are obtained by adjusting the tetrahydrofuran insoluble component ratio and the enthalpy of dissolution (i.e., crystallinity) of the chloroprene polymers.

[0067] The proportion of tetrahydrofuran-insoluble components in chloroprene polymers can be controlled by factors such as polymerization conversion, the amount of chain transfer agent used in the manufacturing process, polymerization time, and polymerization temperature. There is a tendency for longer polymerization time to lead to higher polymerization conversion. Furthermore, increasing the polymerization conversion tends to increase the proportion of tetrahydrofuran-insoluble components in chloroprene polymers. Conversely, increasing the amount of chain transfer agent tends to decrease the proportion of tetrahydrofuran-insoluble components in chloroprene polymers.

[0068] The enthalpy of dissolution (i.e., crystallinity) of chloroprene polymers can be controlled by factors such as the polymerization temperature. There is a tendency for lower polymerization temperatures to result in higher enthalpy of dissolution and higher crystallinity in chloroprene polymers. Furthermore, higher tetrahydrofuran content in chloroprene polymers tends to result in lower enthalpy of dissolution and lower crystallinity.

[0069] When the tetrahydrofuran insoluble component α [mass%] of the chloroprene polymer and the enthalpy of dissolution β [mJ / mg] of the chloroprene polymer satisfy the above formula (1), there is no particular upper limit on the value of Logβ, but it usually satisfies the following formula (2), more preferably satisfies the following formula (2a), and even more preferably satisfies the following formula (2b).

[0070]

[0071]

[0072]

[0073] Chloroprene latex (A) may contain chloroprene-based polymers from various chloroprene latexes. Here, the chloroprene-based polymers from various chloroprene latexes may differ in one or more of their physical properties, such as monomer composition, particle size, tetrahydrofuran insoluble content, and enthalpy of dissolution. For example, chloroprene latex (A) may contain chloroprene-based polymers with the same monomer composition but different tetrahydrofuran insoluble content and enthalpy of dissolution. Furthermore, chloroprene latex (A) may also contain chloroprene-based polymers with approximately the same tetrahydrofuran insoluble content and enthalpy of dissolution but different particle sizes.

[0074] When a chloroprene latex (A) contains chloroprene polymers from various chloroprene latexes, all chloroprene polymers contained in the chloroprene latex (A) must satisfy the stated formula (1). For example, various chloroprene latexes containing chloroprene polymers that do not satisfy the stated formula (1) can be combined so that all chloroprene polymers contained in the resulting chloroprene latex (A) satisfy the stated formula (1). Alternatively, a chloroprene latex containing chloroprene polymers that do not satisfy the stated formula (1) can be combined with a chloroprene latex (A) containing chloroprene polymers that satisfy the stated formula (1) so that all chloroprene polymers contained in the resulting chloroprene latex (A) satisfy the stated formula (1). In addition, a variety of chloroprene latexes (A) containing chloroprene polymers that satisfy the formula (1) can be combined so that all chloroprene polymers contained in the resulting chloroprene latex (A) satisfy the formula (1).

[0075] When chloroprene latex (A) contains multiple chloroprene polymers, based on the view that the chloroprene polymers as a whole readily satisfy formula (1), chloroprene latex (A) preferably contains a first chloroprene polymer with a relatively low percentage of tetrahydrofuran insoluble components and a relatively high enthalpy of solubility, and a second chloroprene polymer with a relatively high percentage of tetrahydrofuran insoluble components and a relatively low enthalpy of solubility. For example, chloroprene latex (A) preferably contains the first chloroprene polymer and the second chloroprene polymer as described below.

[0076] • A chloroprene-based polymer with a tetrahydrofuran insoluble content of 0-15% by mass and a solubility enthalpy of 10-40 mJ / mg.

[0077] • A second chloroprene polymer with a tetrahydrofuran insoluble content of 70-98% by mass and a solubility enthalpy of 0-10 mJ / mg

[0078] The tetrahydrofuran insoluble content of the first chloroprene-based polymer is preferably 0% by mass or more. Furthermore, the tetrahydrofuran insoluble content of the first chloroprene-based polymer is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. The combination of the upper and lower limits of the tetrahydrofuran insoluble content of the first chloroprene-based polymer can be any combination.

[0079] The enthalpy of dissolution of the first chloroprene-based polymer is preferably 10 mJ / mg or more, more preferably 12 mJ / mg or more, and even more preferably 15 mJ / mg or more. The enthalpy of dissolution of the first chloroprene-based polymer is preferably 40 mJ / mg or less, more preferably 37 mJ / mg or less, and even more preferably 35 mJ / mg or less. Furthermore, the combination of the upper and lower limits of the enthalpy of dissolution of the first chloroprene-based polymer can be arbitrary.

[0080] The tetrahydrofuran insoluble content of the second chloroprene-based polymer is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 78% by mass or more. The tetrahydrofuran insoluble content of the second chloroprene-based polymer is preferably 98% by mass or less, more preferably 96% by mass or less, and even more preferably 94% by mass or less. Furthermore, the combination of the upper and lower limits of the tetrahydrofuran insoluble content of the second chloroprene-based polymer can be any combination.

[0081] The enthalpy of dissolution of the 2-chloroprene polymer is preferably 0 mJ / mg or more, more preferably 0.05 mJ / mg or more, and even more preferably 0.10 mJ / mg or more. The enthalpy of dissolution of the 2-chloroprene polymer is preferably 10 mJ / mg or less, more preferably 7 mJ / mg or less, and even more preferably 5 mJ / mg or less. Furthermore, the combination of the upper and lower limits of the enthalpy of dissolution of the 2-chloroprene polymer can be arbitrary.

[0082] Furthermore, both the first chloroprene polymer and the second chloroprene polymer can individually satisfy formula (1), or they can choose not to satisfy formula (1).

[0083] When using the first chloroprene polymer and the second chloroprene polymer, the mass ratio of the first chloroprene polymer to the second chloroprene polymer in the chloroprene latex (first chloroprene polymer: second chloroprene polymer) is not limited as long as all the chloroprene polymers satisfy the above formula (1), but it is preferably 1:99 to 99:1, more preferably 10:90 to 90:10, even more preferably 40:60 to 85:15, and particularly preferably 50:50 to 75:25.

[0084] Here, when the first chloroprene polymer and the second chloroprene polymer coexist, the crystallization rate of the first chloroprene polymer tends to be slower compared to when the first chloroprene polymer exists alone. Therefore, in the chloroprene latex composition (X) in which the first and second chloroprene polymers coexist, the amount of the first chloroprene polymer crystallizing during the drying process to form a layer containing solid components tends to be less than when the first chloroprene polymer exists alone. As a result, compared to when the first chloroprene polymer exists alone, there is a tendency for higher contact (adhesion) immediately after bonding and higher initial adhesive force. Based on these findings, it is believed that a mass ratio of the first chloroprene polymer to the second chloroprene polymer (first chloroprene polymer: second chloroprene polymer) of 50:50 to 75:25 tends to result in particularly good contact and initial adhesion.

[0085] When the first and second chloroprene polymers coexist, even after a relatively long curing period (e.g., 24 hours at 23°C and 50% relative humidity) following bonding, it is believed that the first chloroprene polymer exhibits the same degree of crystallization as when it exists alone. While the crystallized chloroprene polymer has poorer contact compared to its uncrystallized state, its adhesive strength is improved. Therefore, it is speculated that the presence of more first chloroprene polymer than second chloroprene polymer is due to the crystallization of the first chloroprene polymer, resulting in a higher overall adhesive strength of the chloroprene polymers in the chloroprene latex (A).

[0086] The composition and physics of chloroprene polymers that may be contained in chloroprene latex (A) are described below.

[0087] Chloroprene-based polymers are polymers with 2-chloro-1,3-butadiene (also known as 'chloroprene') as the main monomer component. Here, "main monomer component" refers to the component with the highest proportion of monomers comprising structural units in the derived polymer. When the total amount of monomers comprising structural units in the derived polymer is set to 100 parts by mass, the "main monomer component" is preferably a monomer component with a content of 80 parts by mass or more. Chloroprene-based polymers may consist solely of structural units derived from chloroprene, or they may consist of structural units derived from chloroprene and structural units derived from monomers that can copolymerize with chloroprene.

[0088] As monomers that can copolymerize with chloroprene, there are no particular limitations, as long as they do not hinder the purpose of this invention. Examples include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and its esters, and methacrylic acid and its esters. Among these, 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, and methacrylic acid are preferred monomers that can copolymerize with chloroprene; more preferably, 2,3-dichloro-1,3-butadiene and methacrylic acid are preferred; and particularly preferred is 2,3-dichloro-1,3-butadiene.

[0089] The monomers that can copolymerize with chloroprene can be a single type or two or more types.

[0090] The chloroprene-based polymer, wherein the sum of chloroprene and monomers copolymerizable with chloroprene is set to 100 parts by mass, preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and even more preferably 88 parts by mass or more. The amount of structural units derived from chloroprene is preferably 100 parts by mass or less.

[0091] Furthermore, when the chloroprene-based polymer contains structural units derived from 2,3-dichloro-1,3-butadiene, the structural unit may be present in an amount greater than 0 parts by mass, preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 12 parts by mass (however, the total amount of all structural units constituting the chloroprene-based polymer is set to 100 parts by mass). When the total amount of all structural units constituting the chloroprene-based polymer is set to 100 parts by mass, the monomers other than 2,3-dichloro-1,3-butadiene that can copolymerize with chloroprene are preferably 5 parts by mass or less.

[0092] When the composition of the chloroprene polymer in the chloroprene latex composition (X) is within the range described, it can impart cohesiveness and functionality from the comonomer without compromising the softness and high cohesiveness of polychloroprene.

[0093] The z-average particle size of the chloroprene-based polymer particles is preferably 50 nm or more, more preferably 70 nm or more, and even more preferably 90 nm or more. Furthermore, the upper limit of the z-average particle size is preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 210 nm or less. The z-average particle size is determined by the method described in the following examples. The combination of the upper and lower limits of the z-average particle size of the chloroprene-based polymer particles can be arbitrary.

[0094] When the z-average particle size of the chloroprene-based polymer particles is within the specified range, the latex particles exhibit high emulsification stability and are preferred for their long shelf life as adhesive compositions. The z-average particle size of the chloroprene-based polymer particles can be adjusted by the type and amount of surfactant used during polymerization. Specifically, using a surfactant with high emulsifying energy tends to result in a smaller z-average particle size of the obtained chloroprene-based polymer particles. Furthermore, the more surfactant added, the smaller the z-average particle size of the obtained chloroprene-based polymer particles tends to be.

[0095] The enthalpy of dissolution β [mJ / mg] of the chloroprene polymer, as determined by differential scanning calorimetry (DSC), is preferably 0 mJ / mg or more, more preferably 3 mJ / mg or more, and even more preferably 5 mJ / mg or more. The enthalpy of dissolution β [mJ / mg] of the chloroprene polymer is preferably 40 mJ / mg or less, more preferably 25 mJ / mg or less, and even more preferably 20 mJ / mg or less. Furthermore, the enthalpy of dissolution is determined by the method described in the examples described later. The method for modifying the chloroprene polymer to have the desired enthalpy of dissolution is as described above. Furthermore, the combination of the upper and lower limits of the enthalpy of dissolution β [mJ / mg] of the chloroprene polymer can be any combination.

[0096] [Chloroprene Latex (A)]

[0097] Chloroprene latex (A) can be used without limitation as long as it is a latex in which a chloroprene-based polymer satisfying the above requirement (a-1) is dispersed in a dispersion medium such as water. Furthermore, chloroprene latex (A) may also contain a variety of chloroprene latexes.

[0098] When chloroprene latex (A) contains multiple chloroprene latexes, all chloroprene polymers contained in chloroprene latex (A) need to satisfy the stated formula (1). That is, chloroprene latex (A) can be prepared by combining multiple chloroprene latexes containing chloroprene polymers that do not satisfy the stated formula (1), or chloroprene latex (A2) can be formed by combining chloroprene latex containing chloroprene polymers that do not satisfy the stated formula (1) with chloroprene latex (A1) containing chloroprene polymers that satisfy the stated formula (1). In addition, chloroprene latex (A3) containing chloroprene polymers that satisfy the stated formula (1) and chloroprene latex (A4) containing chloroprene polymers that satisfy the stated formula (1) can be mixed to prepare chloroprene latex (A5).

[0099] For example, chloroprene latex (A) may also include the following first chloroprene latex and second chloroprene latex.

[0100] • First-chloroprene latex containing 0-15% by mass of the first-chloroprene polymer and having a solubility enthalpy of 10-40 mJ / mg.

[0101] • Second chloroprene latex containing 70-98% by mass of the tetrahydrofuran-insoluble component and an enthalpy of solubility of 0-10 mJ / mg of the second chloroprene polymer.

[0102] Furthermore, both the first chloroprene latex and the second chloroprene latex can be individually equivalent to chloroprene latex (A), or they may not be equivalent to chloroprene latex (A).

[0103] When the first chloroprene latex is mixed with the second chloroprene latex, the chloroprene polymers in the resulting chloroprene latex readily satisfy the formula (1). As a result, a layer of chloroprene latex (A) containing the solid components of a chloroprene latex composition (X) prepared using chloroprene latex (A) is readily obtained, exhibiting a good tendency for initial adhesion and normal adhesion.

[0104] When the first chloroprene latex and the second chloroprene latex are mixed, the amount of solid component from the first chloroprene latex in 100% by mass of the solid component contained in the chloroprene latex (A) is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 40% by mass or more. Furthermore, the amount of solid component from the first chloroprene latex in 100% by mass of the solid component contained in the chloroprene latex (A) is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 75% by mass or less. Moreover, the combination of the upper and lower limits of the amount of solid component from the first chloroprene latex in 100% by mass of the solid component contained in the chloroprene latex (A) can be any combination.

[0105] When the first chloroprene latex and the second chloroprene latex are mixed, the amount of solid component from the second chloroprene latex in 100% by mass of the solid component contained in the chloroprene latex (A) is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 25% by mass or more. Furthermore, the amount of solid component from the second chloroprene latex in 100% by mass of the solid component contained in the chloroprene latex (A) is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 60% by mass or less. Moreover, the combination of the upper and lower limits of the amount of solid component from the second chloroprene latex in 100% by mass of the solid component contained in the chloroprene latex (A) can be any combination.

[0106] If the first chloroprene latex and the second chloroprene latex are mixed in such a manner that their respective solid components are in the stated proportions, it is presumed that in the resulting chloroprene latex (A), the crystallization of the first chloroprene polymer is hindered by the second chloroprene polymer. As a result, in the chloroprene latex composition (X) containing chloroprene latex (A), the amount of the first chloroprene polymer crystallizing during the drying process to form a layer containing solid components is relatively small, resulting in good contact and initial adhesion of the layer containing solid components. It is presumed here that although the crystallization rate of the first chloroprene polymer is relatively slow, the normal adhesion is good because the crystallization of the first chloroprene polymer proceeds over time.

[0107] The solids concentration of the chloroprene latex (A), when the mass of the chloroprene latex (A) is set to 100% by mass, is preferably 40% by mass or more, more preferably 43% by mass or more, and even more preferably 45% by mass or more. The solids concentration of the chloroprene latex (A), when the mass of the chloroprene latex (A) is set to 100% by mass, is preferably 73% by mass or less, more preferably 71% by mass or less, and even more preferably 70% by mass or less. The combination of the upper and lower limits of the solids concentration of the chloroprene latex (A) can be arbitrary. When the solids concentration of the chloroprene latex (A) is within the above range, it is easy to adjust the solids concentration of the chloroprene latex composition (X) to the preferred range described later. As a result, a chloroprene latex composition (X) with good initial adhesion and normal adhesion can be easily prepared.

[0108] Furthermore, the so-called solids content refers to the components remaining after removing solvents, volatile components, etc., from the latex or emulsion under the conditions for solids content determination. In chloroprene latex (A), the solids content includes not only chloroprene polymers but also emulsifiers used during manufacturing. Specifically, the solids content concentration (mass %) of chloroprene latex (A) is calculated by dividing the weight of the dried solids (Wd) obtained by drying the sampled chloroprene latex (A) in an oven at 100°C for 2 hours by the mass (Wa) of the sampled chloroprene latex (A) and multiplying by 100 (i.e., Wd / Wa×100). The solids content concentration (mass %) of chloroprene latex (A) can be appropriately adjusted by factors such as polymerization conversion rate and the amount of emulsifier used.

[0109] In addition to the chloroprene polymer and the dispersion medium, the chloroprene latex (A) may also contain an emulsifier used in the preparation of the chloroprene latex (A). Preferably, the chloroprene latex (A) contains anionic emulsifiers. More preferably, the chloroprene latex (A) contains rosin salts as the anionic emulsifier. When the chloroprene latex (A) contains anionic emulsifiers, the moderate emulsified state during the drying process is unstable, and it easily exhibits the tackiness important for adhesives. Furthermore, when the anionic emulsifier is a rosin salt, it has good compatibility with the chloroprene polymer and does not hinder the adhesive properties of the chloroprene polymer.

[0110] [Manufacturing method of chloroprene latex (A)]

[0111] There are no particular limitations on the method for obtaining chloroprene latex (A), but emulsion polymerization is preferred, and industrially, aqueous emulsion polymerization is particularly preferred. For example, chloroprene alone, or chloroprene and monomers that can copolymerize with chloroprene, can be emulsified in the presence of an emulsifier, preferably a metal salt of rosin acid, using a polymerization initiator and a chain transfer agent as needed. When a specific polymerization conversion is achieved, a polymerization inhibitor can be added to stop the polymerization.

[0112] There are no particular restrictions on the types of emulsifiers used in chloroprene latex (A), but anionic emulsifiers and nonionic emulsifiers can be listed, with anionic emulsifiers being particularly preferred.

[0113] There are no particular restrictions on the types of anionic emulsifiers, but examples include alkali metal salts of rosin acid, dodecylbenzene sulfonates (sodium dodecylbenzene sulfonate, triethanolamine dodecylbenzene sulfonate, etc.), diphenyl ether sulfonates (sodium diphenyl ether sulfonate, ammonium diphenyl ether sulfonate, etc.), naphthalene sulfonates (sodium salt of β-naphthalene sulfonic acid formaldehyde condensate), and alkali metal salts of fatty acids (potassium laurate, etc.), with alkali metal salts of disproportionated rosin acid being particularly preferred.

[0114] There are no particular limitations on the type of arosin acid, but examples include resin rosin, wood rosin, tall oil rosin, disproportionated rosin that undergoes a disproportionation reaction, and purified rosin, with disproportionated rosin being preferred. Common alkali metal salts are used, preferably sodium and / or potassium salts. Alternatively, arosin acid and an alkali metal hydroxide may be added separately to form an alkali metal salt of arosin acid.

[0115] There are no particular restrictions on the types of nonionic emulsifiers, but examples include polyvinyl alcohol, partially saponified polyvinyl alcohol, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, and polyoxyethylene lauryl ether, with partially saponified polyvinyl alcohol being particularly preferred.

[0116] These emulsifiers can be used alone or in combination of two or more.

[0117] Furthermore, as an emulsifier, it is preferable to include a metal salt of rosin acid.

[0118] When a rosin acid metal salt is included as an emulsifier, its content relative to 100 parts by mass of the added monomer is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more. The upper limit of the content of the rosin acid metal salt is 8 parts by mass or less, more preferably 6.5 parts by mass or less, and even more preferably 5.0 parts by mass or less. By setting the content of the rosin acid metal salt within the aforementioned range, the polymerization stability in emulsion polymerization can be improved, the number of micelles formed can be appropriate to suppress heat generation in the early stage of polymerization, and the viscosity in polymerization can be limited to a specific range. Since the content of the rosin acid metal salt described above is based on the added monomer, it is a value slightly lower than the solids content of the polymer. The combination of the upper and lower limits of the rosin acid metal salt content can be arbitrary.

[0119] The content of rosin acid metal salt in chloroprene latex (A) is preferably 0.55 parts by mass or more, more preferably 1.1 parts by mass or more, and even more preferably 1.65 parts by mass or more, relative to 100 parts by mass of chloroprene polymer in chloroprene latex (A). The upper limit of the rosin acid metal salt content in chloroprene latex (A) is preferably 8.8 parts by mass or less, more preferably 7.15 parts by mass or less, and even more preferably 5.5 parts by mass or less, relative to 100 parts by mass of chloroprene polymer in chloroprene latex (A). The combination of the upper and lower limits of the rosin acid metal salt content in chloroprene latex (A) can be arbitrary.

[0120] As initiators for the polymerization of chloroprene-based polymers, conventional free radical polymerization initiators can be used. For example, in emulsion polymerization, common organic or inorganic peroxides such as benzoyl peroxide, potassium persulfate, and ammonium persulfate, and azo compounds such as azobisisobutyronitrile can be used. Simultaneously, co-catalysts such as anthraquinone sulfonates, potassium sulfite, and sodium sulfite can be appropriately used.

[0121] In the manufacture of chloroprene latex (A), molecular weight regulators (chain transfer agents) may also be used during polymerization to obtain polymers with the desired molecular weight and distribution.

[0122] There are no particular limitations on chain transfer agents, but examples include alkyl xanthate disulfides represented by dithiobis(thiocarboxylic acid) O,O-diisopropyl ester, and alkyl thiols represented by dodecyl thiols.

[0123] Chain transfer agents can be used alone or in combination with two or more.

[0124] In the manufacture of chloroprene latex (A), to obtain polymers with the desired molecular weight and distribution, a polymerization stopper can be added at a specific polymerization conversion point to halt the reaction. There are no particular limitations on the polymerization stopper used; commonly used stoppers such as phenothiazine, p-tert-butylcatechol, hydroquinone, hydroquinone monomethyl ether, and diethylhydroxylamine can be used.

[0125] <Tackifier (B)>

[0126] The tackifier (B) is added to improve the adhesiveness of the chloroprene latex composition (X) and the contactability of the chloroprene-based polymer. In particular, in this case, by adding a specific tackifier, the contactability can be improved in a short-time drying state.

[0127] The amount of tackifier (B) relative to 100 parts by weight of the solid content of the chloroprene latex (A) is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, even more preferably 7 parts by weight or more, and particularly preferably 10 parts by weight or more. Furthermore, the amount of tackifier (B) relative to 100 parts by weight of the solid content of the chloroprene latex (A) is preferably 90 parts by weight or less, more preferably 70 parts by weight or less, and even more preferably 50 parts by weight or less. Moreover, the combination of the upper and lower limits of the amount of tackifier (B) can be arbitrary.

[0128] By including tackifier (B) within the aforementioned range, the adhesiveness of the chloroprene latex composition (X) and the contact adhesiveness of chloroprene-based polymers can be improved. Therefore, the initial adhesive strength, normal adhesive strength, and heat resistance of the chloroprene latex composition (X) are improved. As a result, the layer containing the solid components of the chloroprene latex composition (X) exhibits good contact properties even when used as a contact adhesive in the presence of a dispersion medium, while also exhibiting good initial adhesive strength, normal adhesive strength, and heat resistance.

[0129] The softening point of the tackifier (B) (determined by the ring and ball method (according to the determination method of JIS K 5902)) is 85°C or higher, preferably 90°C or higher, more preferably 95°C or higher. Furthermore, the softening point of the tackifier (B) is 155°C or lower, preferably 150°C or lower, more preferably 147°C or lower, even more preferably 130°C or lower, and particularly preferably 115°C or lower. Moreover, the combination of the upper and lower limits of the softening point can be arbitrary. By ensuring that the softening point of the tackifier (B) is within the above-mentioned range, the adhesiveness of the chloroprene latex composition (X) can be maintained at high temperatures, and its heat resistance can be improved.

[0130] Tackifier (B) can be used alone or in combination of two or more.

[0131] Furthermore, when the thickener (B) is used in an emulsion or solution as described below, the amount of the formulation is the amount of solid components excluding solvents, etc.

[0132] There are no particular limitations on the type of tackifier (B), but examples include rosin resin or rosin ester resin, reaction products of unsaturated carboxylic acids or anhydrides with rosin (rosin resin or rosin ester resin), terpene phenolic resins, aliphatic petroleum resins, alicyclic petroleum resins, aromatic petroleum resins, copolymer petroleum resins, petroleum resins containing their cyanides, alkylphenol resins, etc. The tackifier (B) may also contain carboxyl-containing compounds. When the tackifier (B) contains carboxyl-containing compounds, the carboxyl-containing compounds are preferably reaction products of unsaturated carboxylic acids or anhydrides with rosin. When the tackifier (B) contains carboxyl-containing compounds, there is a tendency for the initial adhesion of the layer containing solid components produced by drying the chloroprene latex composition (X). Here, when the tackifier (B) contains a carboxyl-containing compound, the adhesive layer tends to have good initial adhesion even when the drying time is short enough to result in insufficient drying of the adhesive layer (i.e., the adhesive layer containing the solid component of the chloroprene latex composition (X) has residual dispersion medium). Furthermore, when the tackifier (B) contains a carboxyl-containing compound, the adhesive layer tends to have good initial adhesion even when the solid component of the chloroprene latex composition (X) is dry.

[0133] Examples of rosin resins and rosin ester resins include rosin gum, tall oil rosin, wood rosin, disproportionated rosin, polymerized rosin, their hydrides, their esters, etc. The reaction product of unsaturated carboxylic acids or anhydrides with rosin is a compound obtained by reacting rosin resin or rosin ester resin with unsaturated carboxylic acids or anhydrides. Examples of unsaturated carboxylic acids include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and cinnamic acid. Examples of anhydrides include maleic anhydride and itaconic anhydride. Furthermore, two or more unsaturated carboxylic acids and anhydrides may be used. Here, the two or more unsaturated carboxylic acids used may be two or more unsaturated monocarboxylic acids, two or more unsaturated dicarboxylic acids, or a mixture of one or more unsaturated monocarboxylic acids and one or more unsaturated dicarboxylic acids. Furthermore, at least one unsaturated carboxylic acid and at least one anhydride may be used.

[0134] In the following descriptions, when tackifier (B) contains a reaction product of unsaturated carboxylic acids or anhydrides with rosin, it is sometimes stated as "tackifier (B) is modified by carboxylic acids" or "tackifier (B) is modified by carboxylic acids." On the other hand, when tackifier (B) does not contain a reaction product of unsaturated carboxylic acids or anhydrides with rosin, it is sometimes stated as "tackifier (B) is not modified by carboxylic acids" or "tackifier (B) is not modified by carboxylic acids."

[0135] Examples of terpene phenol resins include hydrogenated terpene phenol resins.

[0136] The tackifier (B) preferably comprises at least one selected from rosin resin, rosin ester resin, reaction products of unsaturated carboxylic acids or anhydrides with rosin (rosin resin or rosin ester resin), terpene phenol resin, and alicyclic petroleum resin. More preferably, the tackifier (B) is at least one selected from rosin ester resin, reaction products of unsaturated carboxylic acids or anhydrides with rosin (rosin resin or rosin ester resin), and terpene phenol resin, particularly preferably rosin ester resin or reaction products of unsaturated carboxylic acids or anhydrides with rosin (rosin resin or rosin ester resin). Furthermore, the rosin resin, rosin ester resin, and alkali metal salt of rosin acid used in the tackifier (B) are different.

[0137] The method of adding tackifier (B) generally involves mixing the tackifier (B) emulsion with the chloroprene latex (A), but the tackifier (B) itself can also be added during the manufacturing process of the chloroprene latex (A). This method is effective as it is one of the methods for adding tackifier (B) for which there is no commercially available emulsion.

[0138] Commercially available tackifiers (B) include rosin-based emulsions such as Arakawa Chemical Industry's SUPERESTER NS-125, Taiwan Arakawa Chemical Industry's E-720W, HARIMA Chemical Industry's HARIESTER SK-218NS, HARIESTER SK-323NS, HARIESTER SK-370N, HARIESTER SK-508H, and HARIESTER SK-816E, and terpene phenolic resin emulsions such as Arakawa Chemical Industry Co., Ltd.'s Tamanol (registered trademark) E-100, Tamanol (registered trademark) E-200NT, Tamanol (registered trademark) E-102A, and Tamanol (registered trademark) E-300NT, and DRT Corporation's Dermulsene TR-602. Additionally, solid tackifiers (B) include alicyclic petroleum resins such as Arakawa Chemical Industry Co., Ltd.'s Alcon (registered trademark) M-135.

[0139] <Chloroprene Latex Composition (X)>

[0140] The chloroprene latex composition (X) comprises the chloroprene latex (A) and the tackifier (B). In addition to the chloroprene latex (A) and the tackifier (B), the chloroprene latex composition (X) may also appropriately contain other components.

[0141] [Other ingredients that may be included in the chloroprene latex composition (X)]

[0142] In the chloroprene latex composition (X), polymers other than chloroprene-based polymers, pH adjusters (C), antioxidants, tackifiers, plasticizers, acid-sensitive agents (zinc oxide, hydrotalcite, etc.), fillers (calcium carbonate, clay, etc.), wetting agents, crosslinking agents (polyisocyanates, polyglycidyl ethers, etc.) may be added as needed, without impairing the performance as an adhesive. One or more of these other components may be used.

[0143] Other polymers that may be included in the chloroprene latex composition (X) besides chloroprene-based polymers include chlorinated polyolefin resins, (meth)acrylic acid polymers, etc., but the chloroprene latex composition (X) preferably does not contain chlorinated polyolefin resins.

[0144] When the chloroprene latex composition (X) contains a (meth)acrylic acid polymer, the content of the (meth)acrylic acid polymer is preferably less than 30 parts by weight, more preferably 15 parts by weight or less, and even more preferably 10 parts by weight or less, relative to 100 parts by weight of the solid content of the chloroprene latex (A). Furthermore, it is particularly preferred that the chloroprene latex composition (X) does not contain a (meth)acrylic acid polymer.

[0145] There are no particular limitations on the type of pH adjuster (C) that may be included in the chloroprene latex composition (X), but preferably, the pH adjuster (C) is a weak acid with at least one of the reciprocal logarithm values ​​(pKa) of the acid dissociation constant at 25°C being 8.0 to 11.0, more preferably 9.0 to 10.0. Furthermore, the upper and lower limits of the pKa of the pH adjuster (C) can be any combination.

[0146] The pH adjuster (C) may be at least one selected from amino acids, organic acids, and inorganic weak acids. Examples of amino acids used as pH adjuster (C) include glycine, aspartic acid, alanine, glutamic acid, valine, glutamine, leucine, arginine, isoleucine, lysine, serine, histidine, threonine, phenylalanine, cysteine, methionine, tryptophan, asparagine, and proline. Examples of organic acids used as pH adjuster (C) include citric acid, acetic acid, and formic acid. Examples of inorganic weak acids used as pH adjuster (C) include boric acid. One or more pH adjusters (C) may be used. Particularly preferred is that the pH adjuster (C) is at least one selected from glycine and boric acid.

[0147] When the chloroprene latex composition (X) contains a pH adjuster (C), the layer containing solid components prepared by drying the chloroprene latex composition (X) tends to have good initial adhesion and heat resistance. When the chloroprene latex composition (X) contains a pH adjuster (C), the adhesive layer tends to have good initial adhesion even when the drying time is short to the extent that the adhesive layer is not sufficiently dried (i.e., when the dispersion medium remains in the adhesive layer containing the chloroprene latex composition (X)).

[0148] When using pH adjuster (C), the product of the amount of pH adjuster (C) used per 100 grams (100g) of solid component of chloroprene latex (A) [mmol] and the valence of pH adjuster (C) is preferably 30 mmol or less, more preferably 20 mmol or less, and even more preferably 15 mmol or less. Furthermore, when using pH adjuster (C), the product of the amount of pH adjuster (C) used per 100 grams of solid component of chloroprene latex (A) [mmol] and the valence of pH adjuster (C) is preferably 0.1 mmol or more, more preferably 0.2 mmol or more, even more preferably 0.3 mmol or more, and even more preferably 0.5 mmol. Moreover, the product of the amount of pH adjuster (C) used [mmol] and the valence of pH adjuster (C) is, in the case of glycine (a monovalent weak acid), the amount in mmol units of glycine, and in the case of citric acid (a trivalent acid), the amount in mmol units of citric acid is three times the amount in mmol units of citric acid. The upper and lower limits of the product of the dosage and valence of pH adjuster (C) can be any combination.

[0149] [Method for manufacturing chloroprene latex composition (X)]

[0150] The chloroprene latex composition (X) is manufactured by mixing the chloroprene latex (A), the tackifier (B), and other ingredients as needed. There are no particular restrictions on the order in which the components are added during mixing.

[0151] [Physical properties of chloroprene latex composition (X)]

[0152] The amount of solids in the chloroprene latex composition (X), when the mass of the chloroprene latex composition (X) is set to 100% by mass, is preferably 40% by mass or more, more preferably 43% by mass or more, and even more preferably 45% by mass or more. The amount of solids in the chloroprene latex composition (X), when the mass of the chloroprene latex composition (X) is set to 100% by mass, is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 58% by mass or less. The combination of the upper and lower limits of the amount of solids in the chloroprene latex composition (X) can be arbitrary.

[0153] When the amount of solid component of the chloroprene latex composition (X) is within the above range, it is easy to achieve good initial adhesion, normal adhesion and heat resistance, and in particular, even when the drying time after attachment to the substrate is short and the moisture in the chloroprene latex composition (X) attached to the surface of the substrate has not completely evaporated, the contact properties are also easy to improve.

[0154] When a first layer, obtained by attaching a chloroprene latex composition (X) to at least a portion of a first substrate and drying it under the following drying conditions, is bonded to a second layer containing solid components, obtained by attaching the same chloroprene latex composition (X) to at least a portion of a second substrate and drying it under the following drying conditions, the bond strength (initial bond strength) at 5 minutes after bonding is preferably 1.5 kN / m or more, more preferably 1.8 kN / m or more, even more preferably 2.0 kN / m or more, and particularly preferably 2.5 kN / m or more. There is no particular upper limit to the initial bond strength, but it is typically 4.0 kN / m. Here, the amount of solid components of the chloroprene latex composition (X) attached to both the first and second substrates is 50 g / m. 2 Furthermore, when using a substrate containing pores into which the chloroprene latex composition (X) can penetrate, such as fabric, the amount of solid component of the chloroprene latex composition (X) after penetrating the pores of the substrate is 50 g / m². 2 .

[0155] In addition, both the first and second layers are layers containing the solid components of the chloroprene latex composition (X), but may contain a dispersion medium from the chloroprene latex composition (X).

[0156] (Drying conditions)

[0157] The drying conditions were 23°C and 50% relative humidity for 10 minutes.

[0158] (Adhesion conditions)

[0159] The first layer and the second layer are brought into contact and placed in a small press machine, where they are pressed at 5 MPa for 3 minutes. Furthermore, the pressing process is carried out at an environment of 23°C and 50% relative humidity.

[0160] The bonding strength (normal adhesion strength) of the test specimen obtained by attaching the chloroprene latex composition (X) to at least a portion of the first substrate and drying it under the stated drying conditions, and then bonding the chloroprene latex composition (X) to at least a portion of the second substrate and drying it under the stated drying conditions, followed by curing at 23°C and 50% relative humidity for 24 hours, is preferably 4.0 kN / m or more, more preferably 4.5 kN / m or more, and even more preferably 5.0 kN / m or more. There is no particular upper limit to the normal adhesion strength, but it is typically 7.0 kN / m. Here, the amount of solid component of the chloroprene latex composition (X) attached to both the first and second substrates is 50 g / m. 2 Furthermore, when using a substrate containing pores into which the chloroprene latex composition (X) can penetrate, such as fabric, the amount of solid component of the chloroprene latex composition (X) after penetrating the pores of the substrate is 50 g / m². 2 .

[0161] In addition, both the first and second layers are layers containing the solid components of the chloroprene latex composition (X), but may contain a dispersion medium from the chloroprene latex composition (X).

[0162] The heat resistance temperature of the test specimen (i.e., the one cured for 24 hours after bonding) was determined by attaching a hook to one corner of the first bonded specimen and suspending it in an oven, while a 1kg hammer was suspended from the second bonded specimen, as shown in the figure. Figure 2 The device suspended in the oven as shown is used to determine this. Specifically, it is as follows: Figure 2 The test specimen is set as shown, and the temperature in the oven is increased at a rate of 0.4°C / min. The temperature at which the second adhesive is completely peeled off from the first adhesive is set as the heat resistance temperature of the chloroprene latex composition (X). The heat resistance temperature is preferably 60°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher. There is no particular upper limit to the heat resistance temperature, but it is typically 120°C.

[0163] The amount of dispersion medium in the layer containing solid components obtained by attaching the chloroprene latex composition (X) to at least a portion of the bonded body at the following adhesion amount and drying under the following drying conditions is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, relative to 100% by mass of the layer containing solid components. There is no particular limitation on the lower limit of the amount of dispersion medium in the layer containing solid components, but it is typically 0.001% by mass.

[0164] (Adhesion amount)

[0165] The solid content of the chloroprene latex composition (X) is set to 50 g / m. 2 Furthermore, when using a substrate containing pores into which the chloroprene latex composition (X) can penetrate, such as fabric, the amount of solid component of the chloroprene latex composition (X) after penetrating the pores of the substrate is 50 g / m². 2 .

[0166] (Drying conditions)

[0167] The drying conditions are 23℃ and 50% relative humidity for 10 minutes.

[0168] ≪Adhesives and Adhesive Products≫

[0169] Chloroprene latex composition (X) is used as an adhesive.

[0170] A chloroprene latex composition (X) is attached to a portion or all of a substrate, and the chloroprene latex composition (X) is dried on the surface of the substrate to form a layer containing the solid components of the chloroprene latex composition (X), thereby obtaining a substrate with an adhesive layer. That is, the layer containing the solid components of the chloroprene latex composition (X) becomes the adhesive layer. Here, the layer containing the solid components may not be completely dried, and may be in a state containing the solid components and a dispersion medium such as water. Examples of substrates to which the chloroprene latex composition (X) can be attached include polyurethane foam, foam, sheets, films, canvas, glass, etc.

[0171] Multiple adherends can also be laminated with the chloroprene latex composition (X) as a separator to manufacture an adhesive article. Here, the multiple adherends can be of the same type, or one adherend (hereinafter referred to as "first adherend") and another adherend (hereinafter referred to as "second adherend") can be of different types. When manufacturing the adherends, after applying a layer containing the solid component of the chloroprene latex composition (X) to both of the multiple adherends to be bonded, the layers of the adherends are brought into contact with each other and bonded to produce an adhesive article. Examples of adhesive articles include furniture and footwear.

[0172] Manufacturing Methods of Adhesive Products

[0173] Adhesive articles can be suitably manufactured, for example, by the following manufacturing methods.

[0174] In other words, bonded products can be manufactured using methods that include the following steps:

[0175] Step (1) of adhering the chloroprene latex composition (X) to at least a portion of each of the first and second adherends.

[0176] Step (2) involves drying the chloroprene latex composition (X) attached to the first substrate and the chloroprene latex composition (X) attached to the second substrate to form a layer containing the solid components of the chloroprene latex composition (X).

[0177] The process (3) of bonding the layer formed on the first substrate to the layer formed on the second substrate by bringing them into contact with each other.

[0178] <Process (1)>

[0179] The following describes an example of a process (step (1)) in which a chloroprene latex composition (X) is attached to a substrate. As a method for attaching the chloroprene latex composition (X) to the substrate, any method that allows the substrate to come into contact with the chloroprene latex composition (X) can be used. For example, the chloroprene latex composition (X) can be applied to the surface of the substrate, or a portion of the substrate can be immersed in a container containing the chloroprene latex composition (X). Alternatively, the chloroprene latex composition (X) can be dripped onto the surface of the substrate. More specifically, methods such as applying with a brush or sprayer, spraying with a sprayer, screen printing, flow coating, spin coating, dipping, and applying to a roller or plate using a bar coater, T-die, T-die with attached bar, doctor blade, roller coating, or die coating can be listed. The adhesion range of the chloroprene latex composition (X) can be the entire surface or a part of the surface of either the first or second substrate.

[0180] <Process (2)>

[0181] In step (2), the chloroprene latex composition (X) attached in step (1) is dried to form a layer containing the solid component of the chloroprene latex composition (X). The thickness of the layer containing the solid component is not particularly limited as long as initial adhesion and normal adhesion are obtained, but is preferably about 20 to 100 μm. The drying time is not particularly limited as long as the layer containing the solid component is formed, but is preferably 5 minutes or more, more preferably 8 minutes or more, preferably 60 minutes or less, and more preferably 45 minutes or less. Furthermore, the combination of the upper and lower limits of the drying temperature can be arbitrary. Regarding the drying temperature, there is no particular limitation as long as the layer containing the solid component is formed, but is preferably 10 to 90°C, more preferably 15 to 80°C.

[0182] The term "drying" in this application does not merely refer to the complete removal of the dispersion medium from the chloroprene latex composition (X), but also includes removing the dispersion medium to the extent that the solid components in the chloroprene latex composition (X) can be formed into layers. Specifically, this includes removing the dispersion medium to a value of 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, for 100% by mass of the layer containing the solid components. Furthermore, the term "drying" in this application does not have a particular lower limit on the amount of dispersion medium in the dried layer containing the solid components, but it is typically 0.001% by mass.

[0183] <Process (3)>

[0184] In step (3), bonding is achieved by bringing the layer containing solid components formed on the surface of the first adherend and the layer containing solid components formed on the surface of the second adherend into contact. As a result, the first adherend and the second adherend are bonded together. To strengthen the bond between the layer containing solid components formed on the surface of the first adherend and the layer containing solid components formed on the surface of the second adherend, pressure may also be applied. Pressure may be applied to the entire bonded article or only to the portions of the first and second adherends in which the layer containing solid components is provided. There are no particular limitations on the method of applying pressure, and there are no particular limitations as long as the pressure is such that it does not cause significant deformation of the layer containing solid components and the adherend.

[0185] [Example]

[0186] The present invention will now be described in more detail with reference to embodiments, but the invention is not limited to these embodiments. Furthermore, in the following description, chloroprene latex that is not equivalent to chloroprene latex (A) will be referred to as chloroprene latex (cA). Similarly, tackifier that is not equivalent to tackifier (B) will be referred to as tackifier (cB), and chloroprene latex composition that is not equivalent to chloroprene latex composition (X) will be referred to as chloroprene latex composition (cX).

[0187] The methods for determining physical properties are as follows.

[0188] <Methods for Determining Physical Properties>

[0189] [Methods for calculating polymerization conversion rate]

[0190] The emulsion of the chloroprene polymer after the start of polymerization was collected, weighed, and dried in an oven at 100°C for 2 hours to obtain a dry solid. The dry solid obtained by drying contains the chloroprene polymer and solid components other than the chloroprene polymer. Therefore, the amount of components that do not volatilize at 100°C from the various components used in emulsion polymerization is calculated based on the amount added during polymerization and the mass of the collected emulsion, and is set as the mass of solid components other than the chloroprene polymer. In addition, the value obtained by subtracting the mass of solid components other than the chloroprene polymer from the mass of the dry solid obtained from the emulsion after the start of polymerization is taken as the "amount of chloroprene polymer generated", and the polymerization conversion rate is calculated by formula (3).

[0191] Polymerization conversion rate [%] = [(amount of chloroprene polymer produced) / (amount of all monomers added)] × 100…(3)

[0192] [tetrahydrofuran insoluble component ratio]

[0193] 1 g of chloroprene latex (A) was added dropwise to 100 ml of tetrahydrofuran. After shaking overnight, the dissolved phase of the supernatant was separated by centrifugation. Shaking and centrifugation were performed at 25 °C. The resulting dissolved phase was heated to 100 °C and the tetrahydrofuran was evaporated for 1 hour. The mass of the dried solids was measured. This yielded the mass of the dissolved fraction in the dissolved phase of the chloroprene polymer.

[0194] By substituting the mass of the chloroprene polymer in 1g of chloroprene diene latex (A) and the mass of the dissolved component mentioned above into equation (4), the content of tetrahydrofuran insoluble component in the chloroprene polymer at 25°C (tetrahydrofuran insoluble component rate) can be calculated.

[0195] Tetrahydrofuran insoluble component percentage (mass%) = {1 - [(mass of dissolved component) / (mass of chloroprene polymer in 1g chloroprene latex (A))]} × 100…(4)

[0196] Furthermore, in formula (4), the mass of the chloroprene polymer in 1g of chloroprene latex (A) is considered as the mass of the solid component obtained by drying 1g of chloroprene latex (A). Moreover, the chloroprene latex (A) is dried by placing it in an oven at 100°C for 2 hours.

[0197] For chloroprene latex (cA), the percentage of tetrahydrofuran-insoluble components is determined using the same method as for chloroprene latex (A).

[0198] [Enthalpy of dissolution of chloroprene polymers]

[0199] 1 g of chloroprene latex (A) was measured in an aluminum pan with a diameter of 4 cm and dried in an oven at 141 °C for 15 minutes to obtain a dry solid. Approximately 10 mg of the dried solid was collected and sealed in a DSC (Digital Scanning Calorimeter) pan for measurement. The DSC was then analyzed using a differential scanning calorimeter (SII DSC7020) under the conditions described below. The resulting DSC curve was analyzed under the following conditions to determine the enthalpy of melting.

[0200] (Measurement conditions)

[0201] The DSC measuring pan containing the sample was heated to 60°C and held at 60°C for 10 minutes to dissolve the crystals in the sample. Next, the sample was cooled to 3°C at a rate of 10°C / min and held at 3°C ​​for 360 minutes to allow the chloroprene polymer in the sample to crystallize. Subsequently, the sample was heated to 80°C at a rate of 10°C / min to dissolve the chloroprene polymer crystals.

[0202] (Analysis Method)

[0203] The slope of the DSC curve (thermal distribution) obtained from DSC measurement was corrected to ensure that the heat variation within the range of 50–60°C above the crystallization melting temperature of the chloroprene polymer was within 2 mW. The flat region of 50–60°C was used as a baseline and extended towards lower temperatures. The enthalpy of crystallization melting of chloroprene diene was calculated based on the peak area enclosed by this baseline and the DSC curve.

[0204] For chloroprene latex (cA), the enthalpy of dissolution was determined using the same method as for chloroprene latex (A).

[0205] [z-average particle size]

[0206] First, the chloroprene latex (A) or the tackifier (B) emulsion used in the examples and comparative examples was diluted with pure water to 0.01~0.1% by mass. For each resulting solution, the z-average particle size was determined using a dynamic light scattering luminance meter (Malvern Panalytical Ltd. ZETASIZER (registered trademark) Nano-S).

[0207] For chloroprene latex (cA) and tackifier (cB), the z-average particle size was also determined using the same method as for chloroprene latex (A).

[0208] [Method for determining the softening point of tackifier (B)]

[0209] Add 5g of thickener (B) to 100mL of tetrahydrofuran and shake for 10 hours using a shaker (SA300) manufactured by Yamato Scientific Co., Ltd. to dissolve it.

[0210] The shaken solution was dripped into 500 mL of methanol, and the resulting solidified material was filtered through an 80-mesh stainless steel screen and dried overnight in a desiccator.

[0211] The resulting dried solidified material was determined according to the ring and ring method of JIS K 5902. The sample was melted at low temperature without generating bubbles, and the molten sample was filled into a ring preheated to a suitable temperature. The softening point was determined in a glycerol bath using an automated softening point evaluation device.

[0212] <Preparation of Chloroprene Latex>

[0213] [Manufacturing Example 1: Preparation of Chloroprene Latex (A-1)]

[0214] In a reactor with an internal volume of 60 liters, add 20.0 kg of 2-chloro-1,3-butadiene (chlorobutadiene), 20 g of n-dodecyl mercaptan, 18 kg of pure water, 700 g of disproportionated rosin acid (manufactured by Arakawa Chemical Industry Co., Ltd., R-600), 180 g of sodium hydroxide, and 120 g of sodium salt of β-naphthalenesulfonic acid formaldehyde condensate. When the total amount of all monomers added is set to 100 parts by mass, the amount of n-dodecyl mercaptan added is 0.1 parts by mass. Emulsify the starting material added to the reactor, and saponify the disproportionated rosin acid with rosin.

[0215] Potassium persulfate was added as an initiator to the emulsion obtained by emulsifying the starting materials, and polymerization was carried out at 20°C under nitrogen atmosphere. When the polymerization conversion reached 75% by mass, a phenothiazine emulsion suspension was immediately added to stop the polymerization. Next, unreacted monomers were removed by steam distillation, and the mixture was concentrated to a solids concentration of 57% by mass to obtain chloroprene latex (A-1) containing chloroprene-based polymers. The tetrahydrofuran-insoluble component of the chloroprene-based polymers in chloroprene latex (A-1) was 0% by mass, the enthalpy of dissolution was 22 mJ / mg, and the z-average particle size was 150 nm.

[0216] The obtained values ​​are shown in Table 1-1. Furthermore, in the following records, Tables 1-1, 1-2, and 1-3 will be collectively referred to as Table 1.

[0217] [Manufacturing Example 2: Preparation of Chloroprene Latex (A-2)]

[0218] In a reactor with an internal volume of 60 liters, 22.0 kg of 2-chloro-1,3-butadiene (chlorobutadiene), 11 g of n-dodecyl mercaptan, 12.5 kg of pure water, 380 g of disproportionated rosin acid (manufactured by Arakawa Chemical Industry Co., Ltd., R-600), 240 g of potassium hydroxide, and 105 g of sodium salt of β-naphthalenesulfonic acid formaldehyde condensate were added. When the total amount of all monomers added was set to 100 parts by mass, the amount of n-dodecyl mercaptan added was 0.05 parts by mass. The starting material added to the reactor was emulsified, and the disproportionated rosin acid was saponified with rosin.

[0219] Potassium persulfate was added as an initiator to the emulsion obtained by emulsifying the starting materials, and polymerization was carried out at 40°C under nitrogen atmosphere. When the polymerization conversion reached 90% by mass, a phenothiazine emulsion suspension was immediately added to stop the polymerization. Next, unreacted monomers were removed by steam distillation to obtain chloroprene latex (A-2) containing chloroprene-based polymers. The tetrahydrofuran-insoluble component of the chloroprene-based polymers in chloroprene latex (A-2) was 86% by mass, with a melting enthalpy of 4.65 mJ / mg and a z-average particle size of 210 nm.

[0220] [Manufacturing Examples 3-4: Preparation of Chloroprene Latex (A-3)-(A-4)]

[0221] Except for variations in the amount of n-dodecyl mercaptan added and the polymerization conversion rate as shown in Table 1, chloroprene latexes (A-3) to (A-4) were prepared using the same method as in Manufacturing Example 2. The physical properties of the chloroprene latexes (A-3) to (A-4) are shown in Table 1.

[0222] [Manufacturing Example 5: Preparation of Chloroprene Latex (A-5)]

[0223] In a reactor with an internal volume of 60 liters, 18.8 kg of chloroprene, 1.2 kg of 2,3-dichloro-1,3-butadiene, 17 kg of pure water, 900 g of disproportionated rosin acid (manufactured by Arakawa Chemical Industry Co., Ltd., R-600), 240 g of potassium hydroxide, and 50 g of sodium salt of β-naphthalenesulfonic acid formaldehyde condensate were added. Here, when the total amount of all monomers added is set to 100 parts by mass, the amount of chloroprene added is 94 parts by mass, and the amount of 2,3-dichloro-1,3-butadiene added is 6 parts by mass. And when the total amount of all monomers added is set to 100 parts by mass, the amount of n-dodecyl mercaptan added is 0 parts by mass. The starting materials added to the reactor were emulsified, and the disproportionated rosin acid was saponified with rosin.

[0224] Potassium persulfate was added as an initiator to the emulsion obtained by emulsifying the starting materials, and polymerization was carried out at 40°C under nitrogen atmosphere. When the polymerization conversion reached 89% by mass, a phenothiazine emulsion suspension was immediately added to stop the polymerization. Next, unreacted monomers were removed by steam distillation to obtain chloroprene latex (A-5) containing chloroprene-based polymers. The tetrahydrofuran-insoluble component of the chloroprene-based polymers in chloroprene latex (A-5) was 85% by mass, with a melting enthalpy of 0.31 mJ / mg and a z-average particle size of 130 nm. The resulting physical properties are shown in Table 1.

[0225] [Manufacturing Examples 6-8: Preparation of Chloroprene Latex (A-6)-(A-8)]

[0226] The chloroprene latex (A-1) obtained in Manufacturing Example 1 was mixed with the chloroprene latex (A-5) obtained in Manufacturing Example 5 to prepare chloroprene latexes (A-6) to (A-8). The mixing ratio of the latexes was 25:75 for the mass of the solid components of chloroprene latex (A-6) to the mass of the solid components of chloroprene latex (A-5). Furthermore, for chloroprene latex (A-7), the mass of the solid components of chloroprene latex (A-1) to the mass of the solid components of chloroprene latex (A-5) was 50:50, and for chloroprene latex (A-8), the mass of the solid components of chloroprene latex (A-1) to the mass of the solid components of chloroprene latex (A-5) was 75:25. The physical properties of chloroprene latex (A-6) to (A-8) are shown in Table 1.

[0227] [Manufacturing Examples 9 and 10: Preparation of Chloroprene Latex (cA-1) and (cA-2)]

[0228] Except for the variations in the monomer ratio added as a starting material, the amount of n-dodecyl mercaptan added, and the polymerization conversion rate as shown in Table 1, chloroprene latexes (cA-1) and (cA-2) were prepared using the same method as in Manufacturing Example 5. The physical properties of chloroprene latexes (cA-1) and (cA-2) are shown in Table 1.

[0229] [Manufacturing Example 11: Preparation of Chloroprene Latex (cA-3)]

[0230] In a reactor with an internal volume of 60 liters, 19.6 kg of chloroprene, 400 g of methacrylic acid, 80 g of n-dodecyl mercaptan, 21 kg of pure water, and 700 g of polyvinyl alcohol (PVA) were added. Here, when the total amount of all monomers added is set to 100 parts by mass, the amount of chloroprene added is 98 parts by mass, and the amount of methacrylic acid added is 2 parts by mass. Furthermore, when the total amount of all monomers added is set to 100 parts by mass, the amount of n-dodecyl mercaptan added is 0.4 parts by mass. The starting materials added to the reactor were emulsified, and the disproportionated rosin acid was saponified with rosin.

[0231] Potassium persulfate was added as an initiator to the emulsion obtained by emulsifying the starting materials, and polymerization was carried out at 40°C under nitrogen atmosphere. When the polymerization conversion reached 100% by mass, the polymerization of the phenothiazine-containing emulsion suspension was stopped. Next, unreacted monomers were removed by steam distillation to obtain chloroprene latex (cA-3) containing chloroprene-based polymers. The tetrahydrofuran-insoluble component of the chloroprene-based polymers in chloroprene latex (cA-3) was 43% by mass, with a melting enthalpy of 0.23 mJ / mg and a z-average particle size of 420 nm.

[0232] [Manufacturing Example 12: Preparation of Chloroprene Latex (cA-4)]

[0233] In Manufacturing Example 5, except for variations in the ratios of the monomers added as starting materials, the amount of n-dodecyl mercaptan added, and the polymerization conversion rate as shown in Table 1, chloroprene latex (cA-4) was prepared using the same method as in Manufacturing Example 5. The physical properties of the chloroprene latex (cA-4) are shown in Table 1.

[0234] [Manufacturing Example 13: Preparation of Chloroprene Latex (cA-5)]

[0235] In Manufacturing Example 2, except for variations in the amount of n-dodecyl mercaptan added and the polymerization conversion rate as shown in Table 1, chloroprene latex (cA-5) was prepared using the same method as in Manufacturing Example 2. The physical properties of the chloroprene latex (cA-5) are shown in Table 1.

[0236] [Manufacturing Examples 14-16: Preparation of Chloroprene Latex (A-9) to (A-11)]

[0237] In Manufacturing Example 2, except for varying the ratio of each monomer, the amount of n-dodecyl mercaptan, and the polymerization conversion rate as shown in Table 1, chloroprene latexes (A-9) to (A-11) were prepared using the same method as in Manufacturing Example 2. The physical properties of the chloroprene latexes (A-9) to (A-11) are shown in Table 1.

[0238] [Manufacturing Example 17: Preparation of Chloroprene Latex (A-12)]

[0239] The chloroprene latex (A-1) obtained in Manufacturing Example 1 was mixed with the chloroprene latex (A-11) obtained in Manufacturing Example 16 to prepare chloroprene latex (A-12). The mixing ratio of the latexes was 50:50, where the mass of the solids in the chloroprene latex (A-1) was equal to the mass of the solids in the chloroprene latex (A-11). The physical properties of the chloroprene latex (A-12) are shown in Table 1.

[0240] [Manufacturing Example 18: Preparation of Chloroprene Latex (A-13)]

[0241] In Manufacturing Example 1, except that the ratio of each monomer added, the amount of n-dodecyl mercaptan added, and the polymerization conversion rate are shown in Table 1, and no concentration treatment is performed, chloroprene latex (A-13) was prepared using the same method as in Manufacturing Example 1. The physical properties of the chloroprene latex (A-13) are shown in Table 1.

[0242] [Manufacturing Example 19: Preparation of Chloroprene Latex (A-14)]

[0243] The chloroprene latex (A-5) obtained in Manufacturing Example 5 was mixed with the chloroprene latex (A-13) obtained in Manufacturing Example 18 to prepare chloroprene latex (A-14). The mixing ratio of the latexes was 50:50, where the mass of the solids in the chloroprene latex (A-5) was equal to the mass of the solids in the chloroprene latex (A-13). The physical properties of the chloroprene latex (A-14) are shown in Table 1.

[0244] For each of the obtained chloroprene latexes (A-1) to (A-10), (A-12), (A-14), and (cA-1) to (cA-5), a graph is plotted on the Logβ value calculated based on the enthalpy of dissolution β (mJ / mg) of the chloroprene polymer relative to the percentage of tetrahydrofuran-insoluble components of the chloroprene polymer. Figure 1 . Figure 1 The straight line in the equation is represented by equation (1).

[0245] like Figure 1 As shown, chloroprene latexes (A-1) to (A-10), (A-12), and (A-14) all satisfy equation (1). On the other hand, chloroprene latexes (cA-1) to (cA-5) do not satisfy equation (1).

[0246]

[0247] <Raw Materials>

[0248] The following materials were used in the following examples and comparative examples.

[0249] Chloroprene latex

[0250] The chloroprene latexes (A-1) to (A-10), (A-12), (A-14), and (cA-1) to (cA-5) manufactured in Examples 1 to 15, 17, and 19 described above.

[0251] [Tackifier]

[0252] • "Tackifier (B-1)": Rosin-based emulsion (manufactured by HARIMA Chemical Co., Ltd., HARIESTER SK-370N, softening point = 100°C, solid content 50% by mass, z-average particle size = 450nm, containing the reaction product of unsaturated carboxylic acid and rosin)

[0253] • "Tackifier (B-2)": Rosin-based emulsion (manufactured by HARIMA Chemical Co., Ltd., HARIESTER SK-816E, softening point = 145°C, solid content 50% by mass, z-average particle size = 270nm, does not contain reaction products of unsaturated carboxylic acids and rosin)

[0254] • "Tackifier (B-3)": Rosin-based emulsion (manufactured by HARIMA Chemical Co., Ltd., HARIESTER NS-125, softening point = 125°C, solid content 50% by mass, z-average particle size = 440nm, containing the reaction product of unsaturated carboxylic acid and rosin)

[0255] • "Tackifier (cB-1)": Rosin-based emulsion (made by CLAYTON POLYMER, Aquatac 2680, softening point = 80°C, solid content 54% by mass, z-average particle size = 280nm, excluding reaction products of unsaturated carboxylic acids and rosin)

[0256] • "Tackifier (cB-2)": Rosin-based emulsion (manufactured by Arakawa Kogyo Co., Ltd., TAMANOL E-900NT, softening point = 160°C, solid content 54% by mass, z-average particle size = 270nm, does not contain reaction products of unsaturated carboxylic acids and rosin)

[0257] • "Tackifier (cB-3)": Rosin-based emulsion (manufactured by HARIMA Chemical Co., Ltd., HARIESTER SK-822E, softening point = 170°C, solid content 50% by mass, z-average particle size = 270nm, does not contain reaction products of unsaturated carboxylic acids and rosin)

[0258] [pH adjuster (C)]

[0259] • "pH adjuster (C-1)": Glycine (manufactured by Resonac), pKa2=9.6

[0260] • "pH adjuster (C-2)": Boric acid (manufactured by Kanto Chemical Co., Ltd.), pKa=9.2

[0261] In addition, both glycine and acid are monovalent weak acids.

[0262] <Example 1>

[0263] [Preparation of Chloroprene Latex Composition (X-1)]

[0264] In chloroprene latex (A-1), tackifier (B-1) is added in an amount of 30 parts by mass relative to 100 parts by mass of solid components in chloroprene latex (A-1) to prepare chloroprene latex composition (X-1).

[0265] [Preparation of test specimens for evaluating bond strength]

[0266] Apply 100g (solids content) / m² of coating to each of two No. 6 canvas sheets (25mm wide x 150mm long, coating surface 25mm wide x 100mm long) using a brush. 2 The chloroprene latex composition (X-1) was dried at 23°C and 50% relative humidity for 30 minutes. Subsequently, it was dried again at 50 g (solids content) / m³. 2 After applying the chloroprene latex composition (X-1), the substrate is dried at 23°C and 50% relative humidity for 10 minutes to form a substrate containing a layer of solid components of the chloroprene latex composition (X-1). Two substrates are then brought into contact with each other with the solid component layers and bonded together using a small press at a pressure of 5 MPa for 3 minutes to obtain a test piece for evaluating the bond strength.

[0267] [Initial adhesion]

[0268] The prepared test specimens for evaluating adhesive strength were cured at 23°C and 50% relative humidity for 2 minutes (i.e., including the 5 minutes of bonding time after pressing with a small press), and the initial adhesive strength (kN / m) was determined according to JIS K 6854-3-1999. The peeling speed was 200 mm / min. Furthermore, the initial adhesive force was evaluated according to the following evaluation criteria. The obtained initial adhesive force and its evaluation results are shown in Table 2-1. In the following description, Table 2-1 and Table 2-2 are collectively referred to as Table 2.

[0269] (Evaluation Criteria)

[0270] SS: Initial adhesive strength is above 2.5kN / m.

[0271] AA: Initial adhesive strength is above 1.5kN / m and less than 2.5kN / m.

[0272] CC: Initial adhesive force is less than 1.5 kN / m.

[0273] [Normal Adhesion]

[0274] The test specimens for evaluating adhesive strength were cured at 23°C and 50% relative humidity for 24 hours. The adhesive force was measured according to JIS K 6854-3-1999 and taken as the normal adhesive force (kN / m). The peeling speed was 200 mm / min. Furthermore, the obtained normal adhesive force was evaluated according to the following evaluation criteria. The obtained normal adhesive force and its evaluation results are shown in Table 2.

[0275] (Evaluation Criteria)

[0276] SS: Normal adhesion strength is above 5.0kN / m.

[0277] AA: Normal adhesion strength is above 4.0kN / m and less than 5.0kN / m.

[0278] CC: Normal adhesion strength is less than 4.0 kN / m.

[0279] [Heat Resistance Test]

[0280] After curing the adhesive strength evaluation specimens at 23°C and 50% relative humidity for 24 hours, they were cut into 25mm x 25mm portions with and 25mm x 25mm portions without adhesive coating, forming 25mm x 50mm heat resistance test specimens. A hook was attached to one end of the uncoated portion of the heat resistance test specimen, and the specimen was suspended in an oven set at 40°C. A 1kg hammer was suspended from the other end of the uncoated portion. An example of the heat resistance test specimen suspended in the oven is shown below. Figure 2 .

[0281] After maintaining the oven temperature at 40°C for 30 minutes, the temperature was increased at a rate of 0.4°C / min, and the temperature at which the adhesive surfaces of the heat resistance test specimens completely peeled off (°C) was recorded. Furthermore, the obtained heat resistance temperatures were evaluated according to the following evaluation criteria. The obtained heat resistance temperatures and their evaluation results are shown in Table 2.

[0282] (Evaluation Criteria)

[0283] SS: Heat resistance temperature above 70℃.

[0284] AA: Heat resistance temperature is above 60℃ and below 70℃.

[0285] CC: Heat resistance temperature less than 60℃.

[0286] <Examples 2-8, 14-17, Comparative Examples 1-5>

[0287] Except for changing the type of chloroprene latex used in preparing the chloroprene latex composition as shown in Table 2, the preparation of chloroprene latex composition (X) or chloroprene latex composition (cX), the preparation of test pieces, and the testing using the test pieces were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0288] <Determination of the proportion of water in the layer containing solid components>

[0289] The determination of the water content in the layer containing solid components was performed using the chloroprene latex composition (X-7) prepared in Example 7 as the chloroprene latex composition (X).

[0290] Apply 100g (solids content) / m² of coating to a No. 6 canvas (25mm wide x 150mm long, coating area 25mm wide x 100mm long) using a brush. 2 The chloroprene latex composition (X-7) was dried at 23°C and 50% relative humidity for 1 hour, and the weight of the resulting sample (W1) was measured. Subsequently, the resulting sample was coated again with 50 g (solid component) / m² of [a specific coating material]. 2 After preparing the chloroprene latex composition (X-7), it was dried at 23°C and 50% relative humidity for 10 minutes to form a test piece with a layer of solid components containing the chloroprene latex composition (X-7) attached. The mass (W) of the obtained test piece was weighed. 湿 Subsequently, the specimen with the layer containing the solid component was placed in an oven at 100°C for 1 hour to allow the solid component layer to dry completely, and the mass (W) after drying was determined. 干 After calculating the proportion of water in the layer containing solid components using the following formula, 30% of the mass of the layer containing solid components is water (dispersion medium) out of 100% by mass.

[0291] The percentage of water contained in the solid components [mass%] =

[0292] ((W 湿 -W1)-(W 干 -W1)) / (W 湿 -W1)×100

[0293] Furthermore, since the drying conditions for making the layer containing solid components were the same in embodiments other than Example 7, the proportion of water (dispersion medium) contained in the layer containing solid components is considered to be about 30% by mass out of 100% by mass of the layer containing solid components.

[0294]

[0295] Furthermore, the amount of tackifier (B-1) is the amount (parts by mass) of the solid component of tackifier (B-1) relative to 100 parts by mass of the solid component of chloroprene latex. Additionally, "z-average particle size*" refers to the z-average particle size of the chloroprene latex.

[0296]

[0297] Furthermore, the amount of tackifier (B-1) is the amount (parts by mass) of the solid component of tackifier (B-1) relative to 100 parts by mass of the solid component of chloroprene latex. Additionally, "z-average particle size*" refers to the z-average particle size of the chloroprene latex.

[0298] <Example 9, Comparative Examples 6-8>

[0299] Except for changing the type of tackifier used in preparing the chloroprene latex composition as shown in Table 3, the preparation of the chloroprene latex composition, the preparation of test pieces, and the testing using the test pieces were performed in the same manner as in Example 1. The results obtained are shown in Table 3 together with the results of Example 1. In Table 3, when the tackifier contains the reaction product of unsaturated carboxylic acid and rosin, it is recorded as the tackifier having carboxylic acid modification. On the other hand, when the tackifier does not contain the reaction product of unsaturated carboxylic acid and rosin, it is recorded as the tackifier not having carboxylic acid modification.

[0300] <Example 23>

[0301] Except for changing the type of tackifier used in preparing the chloroprene latex composition as shown in Table 3, the preparation of the chloroprene latex composition, the preparation of test pieces, and the testing using the test pieces were performed in the same manner as in Example 7. The results obtained are shown together with the results of Example 7 in Table 3.

[0302]

[0303] Furthermore, the amount of tackifier is the amount (parts by mass) of the solid component of the tackifier relative to 100 parts by mass of the solid component of the chloroprene latex. Additionally, "z-average particle size*" refers to the z-average particle size of the chloroprene latex.

[0304] <Examples 10-13, Comparative Examples 9 and 10>

[0305] Except for changing the amount of tackifier (B) used in preparing the chloroprene latex composition relative to 100 parts by mass of the solids in the chloroprene latex (A) as shown in Table 4, the preparation of the chloroprene latex composition, the preparation of test pieces, and the testing using the test pieces were performed in the same manner as in Example 7. The results obtained are shown together with the results of Example 7 in Table 4.

[0306]

[0307] Furthermore, the amount of tackifier (B-1) is the amount (parts by mass) of the solid component of tackifier (B-1) relative to 100 parts by mass of the solid component of chloroprene latex. Additionally, "z-average particle size*" refers to the z-average particle size of the chloroprene latex.

[0308] <Example 18>

[0309] 100g of the solids in chloroprene latex (A-14) is defined as 100 parts by weight. In chloroprene latex (A-14), tackifier (B-1) is added in an amount of 30 parts by weight relative to 100 parts by weight of the solids in chloroprene latex (A-14), and 0.06 parts by weight (i.e., 0.80 mmol) of pH adjuster (C-1) is added to prepare a chloroprene latex composition (X-18).

[0310] Except that a chloroprene latex composition (X-18) was used instead of a chloroprene latex composition (X-17), the preparation and testing of the test pieces were performed in the same manner as in Example 17. The results obtained are shown together with those of Example 17 in Table 5.

[0311] <Examples 19-22>

[0312] Except for changing the amount and type of pH adjuster used in preparing the chloroprene latex composition as shown in Table 5, the preparation of the chloroprene latex composition, the preparation of test pieces, and the testing of the test pieces were carried out in the same manner as in Example 17. That is, in Examples 19-22, 100g of the solid component in the chloroprene latex (A-14) was set as 100 parts by mass. The results are shown in Table 5.

[0313]

[0314] In Table 5, the values ​​in the tackifier (B-1) column represent the amount (parts by mass) of the solid component of tackifier (B-1) relative to 100 parts by mass of the solid component of chloroprene latex. The amount of pH adjuster (C) in Table 5 represents the amount per 100 parts by mass of the solid component of chloroprene latex. Furthermore, "z-average particle size*" refers to the z-average particle size of the chloroprene latex.

Claims

1. A chloroprene latex composition (X), comprising: Chloroprene latex (A) containing a chloroprene-based polymer that satisfies the following requirement (a-1), and Tackifier (B) with a softening point of 85℃~155℃ determined by the ring and ball method, which is based on the determination method of JIS K 5902. Requirement (a-1): The tetrahydrofuran insoluble component percentage α in 100% by mass of the chloroprene polymer and the enthalpy of dissolution β of the chloroprene polymer determined by differential scanning calorimetry (DSC) satisfy the following equation (1), wherein, The unit of the insoluble component percentage α of tetrahydrofuran is mass%, and the unit of the enthalpy of dissolution β is mJ / mg. 。 2. The chloroprene latex composition (X) according to claim 1, wherein the chloroprene latex (A) comprises: First chloroprene latex containing 0-15% by mass of tetrahydrofuran-insoluble components and an enthalpy of solubility of 10-40 [mJ / mg] of chloroprene-based polymers, and Second chloroprene latex containing 70-98% by mass of tetrahydrofuran-insoluble components and having a solubility enthalpy of 0-10 [mJ / mg] of chloroprene polymers.

3. The chloroprene latex composition (X) according to claim 2, wherein of the 100% by mass of solid components contained in the chloroprene latex (A), the content of solid components from the first chloroprene latex is 1 to 99% by mass, and the content of solid components from the second chloroprene latex is 99 to 1% by mass.

4. The chloroprene latex composition (X) according to claim 1, wherein the chloroprene latex (A) comprises an anionic emulsifier.

5. The chloroprene latex composition (X) according to claim 4, wherein the anionic emulsifier is rosin acid salt.

6. The chloroprene latex composition (X) according to claim 1, wherein the tetrahydrofuran insoluble component percentage α and the enthalpy of dissolution β satisfy the following formula (2), wherein, The unit of the insoluble component percentage α of tetrahydrofuran is mass%, and the unit of the enthalpy of dissolution β is mJ / mg. 。 7. The chloroprene latex composition (X) of claim 1, wherein the tackifier (B) comprises a carboxyl-containing compound.

8. The chloroprene latex composition (X) of claim 7, wherein the tackifier (B) comprises a reaction product of an unsaturated carboxylic acid or anhydride with rosin.

9. The chloroprene latex composition (X) of claim 8, wherein the unsaturated carboxylic acid or anhydride is selected from at least one of acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride and cinnamic acid.

10. The chloroprene latex composition (X) according to claim 1, comprising 3 to 90 parts by weight of the tackifier (B) relative to 100 parts by weight of the solids component of the chloroprene latex (A).

11. The chloroprene latex composition (X) according to claim 1, wherein when the mass of the chloroprene latex composition (X) is set to 100% by mass, the amount of solid component of the chloroprene latex composition (X) is 40 to 70% by mass.

12. The chloroprene latex composition (X) of claim 1, further comprising a pH adjuster (C).

13. The chloroprene latex composition (X) of claim 12, wherein the pH adjuster (C) is selected from at least one of amino acids, organic acids, and inorganic weak acids.

14. The chloroprene latex composition (X) of claim 12, wherein the pH adjuster (C) is at least one weak acid whose reciprocal logarithm of the acid dissociation constant at 25°C, pKa, falls within the range of 8.0 to 11.

0.

15. The chloroprene latex composition (X) of claim 12, wherein the product of the amount of pH adjuster (C) used relative to 100 grams of the solid component of the chloroprene rubber (A) and the valence of the pH adjuster (C) is 0.1 to 30 mmol, wherein the unit of the amount used is mmol.

16. A method for manufacturing an adhesive article, comprising the following steps: The step (1) of attaching the chloroprene latex composition (X) according to any one of claims 1 to 15 to at least a portion of each of the first substrate and the second substrate, The step (2) involves drying the chloroprene latex composition (X) attached to the first bonded body and the chloroprene latex composition (X) attached to the second bonded body to form a layer containing the solid components of the chloroprene latex composition (X), and... The process (3) of bonding the layers formed on the first adhesive body and the layers formed on the second adhesive body by bringing them into contact with each other.

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