JP2007262230A - Natural rubber-based adhesive composition and method for suppressing yellowing of coated material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive composition capable of effectively suppressing the yellowing of a coated material without deteriorating the characteristic properties of adhesive compositions such as adhesive force, rubber elasticity, film hardness, tack strength and holding force. <P>SOLUTION: The natural rubber-based adhesive composition contains (A) a latex adhesive component produced by compounding (A-1) natural rubber or a modified natural rubber and (A-2) other polymers at a mass ratio of 30:70 to 100:0 (solid basis) and (B) 0.1-10 pts.mass of an amine based on 100 pts.mass of the component A (solid basis). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a latex adhesive composition containing natural rubber or modified natural rubber as a constituent component. More specifically, an adhesive composition that can suppress yellowing of the coated body without deteriorating the original properties of the adhesive composition such as adhesive strength, rubber elasticity, film hardness, adhesive strength, and holding power. The present invention relates to a method for suppressing yellowing of a coated body on which a coating layer made of an article and an adhesive composition is formed.

  Conventionally, latex adhesives composed of natural rubber (hereinafter referred to as “natural rubber adhesives”) include contact adhesives for albums and fabrics, carpet backing materials, and adhesive tapes. It is widely used as an adhesive for fibers or paper sheets (see, for example, Patent Document 1).

JP 2001-81105 A

  However, when the present inventors examined the natural rubber adhesive, when the coated body is formed by applying the adhesive to the surface of the base material, the coated body may turn yellow. Obtained knowledge. That is, the conventional natural rubber-based adhesive has a problem that the coated body may be yellowed, and is not sufficiently satisfactory in that such a problem is unsolved. It was.

  As described above, at present, a natural rubber adhesive that can effectively suppress yellowing of the coated body has not been disclosed yet. A natural rubber adhesive that can effectively suppress yellowing of the coated body without diminishing the original properties of the adhesive composition such as adhesive strength, rubber elasticity, film hardness, adhesive strength, and holding power. It is eager to create.

  The present invention has been made to solve the above-described problems of the prior art, and without diminishing the original properties of the adhesive composition such as adhesive strength, rubber elasticity, film hardness, adhesive strength, and holding strength. Provided is a natural rubber adhesive composition capable of effectively suppressing yellowing of a coated body and a method for suppressing yellowing of a coated body formed with a coating layer comprising the adhesive composition It is.

  As a result of intensive studies to solve the problems of the prior art as described above, the present inventors have heretofore known amines that have been known as substances that cause yellowing of coated bodies against natural rubber adhesives. The present invention was completed by conceiving that the above-mentioned problems were unexpectedly solved by blending the above. Specifically, the present invention provides the following adhesive composition and method for suppressing yellowing of the coated body.

[1] (A component): (A-1 component) Natural rubber or modified natural rubber and (A-2 component) other polymer is blended at a mass ratio (in terms of solid content) of 30:70 to 100: 0. The latex adhesive component and (B component): amine are contained, and the B component is in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass (in terms of solid content) of the A component. A natural rubber-based adhesive composition.
[2] Further, (Component C): Adhesion according to [1] above, which contains silica and the C component is blended within a range of 10 to 600 parts by mass with respect to 100 parts by mass of the A component. Agent composition.

[3] Mass ratio of (A component): (A-1 component) natural rubber or modified natural rubber and (A-2 component) other polymer is 30:70 to 100: 0 on the surface of the base material ( In a coated body in which a coating layer made of a natural rubber-based adhesive composition containing a latex adhesive component formulated in terms of solid content is formed, (B component): amine with respect to the coating layer The method of suppressing yellowing of the said coated body by coating thru | or spraying.

[4] The method according to [3], wherein the B component is applied or dispersed within a range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the A component.

  Since the adhesive composition of the present invention contains an amine as a constituent component, the inherent properties of the adhesive composition such as adhesive strength, rubber elasticity, film hardness, adhesive strength, and holding power are not diminished. Yellowing can be effectively suppressed. Moreover, since the method of the present invention applies or spreads amine to the coated body on which the coating layer made of the adhesive composition is formed, yellowing of the coated body can be effectively suppressed. .

  Hereinafter, the best mode for carrying out the adhesive composition of the present invention and the method for suppressing yellowing of the coated body will be specifically described. However, the present invention includes all embodiments including the invention-specific matters, and is not limited to the embodiments described below. In this specification, “(meth) acryl” means that both “acryl” and “methacryl” are included.

[1] Adhesive composition:
The adhesive composition of the present invention comprises (A component): (A-1 component) natural rubber or modified natural rubber and (A-2 component) other polymer in a mass ratio of 30:70 to 100: 0 ( It is a natural rubber adhesive composition containing a latex-like adhesive component formulated in terms of solid content) and (B component): amine. Hereinafter, it demonstrates for every component.

[1-A] Latex adhesive component (component A):
The “latex-like adhesive component” referred to in the present specification includes natural rubber or modified natural rubber (component A-1) as an essential component, and other polymers (component A-2) are blended depending on the purpose. Means latex. The latex adhesive component (hereinafter referred to as “component A”) exhibits the adhesive properties of the adhesive composition of the present invention.

  As the component A, for example, a modified natural rubber latex obtained by modifying natural rubber particles in the natural rubber latex with other components can be used. Moreover, you may use the latex obtained by mixing another polymer with the modified natural rubber latex.

[1-A-1] Natural rubber or modified natural rubber (A-1 component):
“Natural rubber” means a naturally occurring rubber and is usually obtained as “natural rubber latex” in which natural rubber particles are dispersed in a medium such as water. This “natural rubber latex” can also be used as a raw material when preparing the adhesive composition of the present invention. In the present invention, any material generally referred to as “natural rubber latex” can be used without particular limitation. Specifically, natural rubber latex such as high ammonia type, low ammonia type or deproteinization type can be suitably used.

  It is preferable to use a natural rubber latex having an MST (Mechanical Stability Time), which is an indicator of mechanical stability, of 1000 to 3000 seconds. The use of natural rubber latex having an MST in the range of 1000 to 3000 seconds makes it easy to modify the adhesive composition, and does not reduce the film properties (film hardness, etc.) of the adhesive composition. The mechanical stability of the object can be improved. On the other hand, when a natural rubber latex having an MST of less than 1000 seconds is used, the resulting adhesive composition may have insufficient mechanical stability. In addition, natural rubber latex having an MST of more than 3000 seconds often improves mechanical stability by adding a large amount of a surfactant, so that it is difficult to modify it or the resulting adhesive composition The film physical properties (film hardness, etc.) of the object may be insufficient.

  As used herein, “modified natural rubber” means natural rubber modified by other components. Usually, a natural rubber latex is used as a raw material, and natural rubber particles in the natural rubber latex are modified with other components to obtain a latex-like modified natural rubber.

  The “other component (hereinafter sometimes referred to as“ modifying component ”)” for modifying the natural rubber is preferably a polymer, and more preferably a polymer formed from a vinyl monomer. preferable. Such a modified natural rubber can be obtained, for example, by polymerizing a monomer (for example, a vinyl monomer) in natural rubber latex.

  As the monomer used for modification, a vinyl monomer is preferable. Examples include (meth) acrylic acid ester monomers, aromatic vinyl monomers, vinyl cyanide monomers, ethylenically unsaturated acid monomers, ethylenically unsaturated alcohols and esters thereof, and ethylenically unsaturated silanes. . In the modification, these monomers can be used alone or in combination of two or more.

  “(Meth) acrylic acid ester monomer” is a (meth) acrylic acid ester monomer used in conventional aqueous acrylic emulsions, that is, acrylic acid or methacrylic acid, aliphatic alcohol, and alicyclic alcohol. Or esters with aromatic alcohols.

  Specific compounds include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (meth ) Pentyl acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate Undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylic acid Benzyl etc. can be mentioned.

  In addition, (meth) acrylic acid alkyl esters having an epoxy group (for example, glycidyl (meth) acrylate) and (meth) acrylic acid cycloalkyl esters having an optionally substituted cycloalkyl group (for example, ( (Meth) acrylic acid cyclohexyl, etc.), (meth) acrylic acid esters having a hydroxyalkyl group containing a hydroxyl group (for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate) Etc.) can also be used. Of these monomers, methyl methacrylate is particularly preferred.

  Examples of the “aromatic vinyl monomer” include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, p-methoxystyrene, p-aminostyrene, p -Acetoxystyrene, sodium styrenesulfonate, etc. can be mentioned.

  Examples of the “vinyl cyanide monomer” include acrylonitrile, methacrylonitrile, vinylidene cyanide, α-methoxyacrylonitrile and the like.

  Examples of the “ethylenically unsaturated acid monomer” include ethylenically unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, fumaric acid, fumaric anhydride, maleic acid, maleic anhydride; vinyl sulfonic acid, isoprene sulfone Examples thereof include ethylenically unsaturated sulfonic acids such as acids.

  Examples of the “ethylenically unsaturated alcohol and ester thereof” include allyl alcohol, methallyl alcohol, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, allyl acetate, methallyl caproate, and allyl laurate. And allyl benzoate.

  Examples of the “ethylenically unsaturated silane” include vinyltriethylsilane, methylvinyldichlorosilane, dimethylallylchlorosilane, vinyltrichlorosilane and the like.

  The amount of the vinyl monomer used for the modification is preferably 0 to 60 parts by mass, more preferably 10 to 50 parts by mass with respect to 100 parts by mass (converted to solid content) of natural rubber, and 15 to 40 parts by mass. It is particularly preferable to use parts by mass. By setting the amount of the vinyl monomer to 5 to 60 parts by mass, a sufficient modification effect can be obtained while maintaining the adhesive force. On the other hand, when the amount of the vinyl monomer is less than 5 parts by mass, the modification effect (improvement of cohesive force, mechanical stability, weather resistance, etc.) may be insufficient. On the other hand, when the amount of the vinyl monomer exceeds 60 parts by mass, the physical properties of the film possessed by the natural rubber may change and the adhesive strength may decrease.

  Examples of the form of “modification” include (1) a form in which at least a part of the surface of natural rubber particles is coated with particles or a coating layer of the modification component, and (2) a modification component inside the natural rubber particle. (3) A form in which at least a part of the surface of the natural rubber particles is covered with the modifying component particles or the coating layer and is also present inside the natural rubber particles. Among these forms, the form (3) is particularly preferable. Furthermore, it is preferable that the modified components take the forms (1) to (3) in a state of being grafted to natural rubber molecules.

  The “modified natural rubber” preferably takes the modified form of (3) above, but such a shape is obtained by simply mixing a natural rubber latex with a synthetic resin emulsion having the above-mentioned particle size. It can be obtained by mixing natural rubber and monomer components and then polymerizing them. Specifically, it can be obtained by mixing a natural rubber latex containing natural rubber particles and a vinyl monomer, followed by polymerization. The polymerization method may be any method as long as a modified natural rubber in which the surface of natural rubber particles is coated with a vinyl polymer is obtained.

[1-A-2] Other polymer (component A-2):
As used herein, “other polymer” means a polymer other than natural rubber and modified natural rubber. The “other polymer” is an optional component unlike the modified natural rubber, but the addition of the other polymer has the advantage that the cohesive strength of the coating layer formed from the adhesive composition is improved. It is preferable.

  Examples of the “other polymer” include styrene-butadiene copolymer (SBR), methyl methacrylate-butadiene copolymer (MBR), styrene-isoprene copolymer (SIR), and styrene-isoprene-styrene block copolymer. Copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), acrylic ester copolymer (AE), vinyl acetate copolymer (EVA), olefin copolymer, urethane copolymer, epoxy copolymer Examples thereof include a polymer, a vinyl alcohol copolymer (PVA), an isoprene polymer (IR), a butadiene polymer (BR), a chloroprene polymer (CR), a nitrile-butadiene copolymer (NBR), and polystyrene. Among these polymers, it is preferable to use SBR, MBR, NBR, CR or AE because the effect of improving the cohesive force of the formed coating layer is high.

  Further, since the component A is a latex adhesive component, the “other polymer” is preferably a polymer that can be dissolved or dispersed in a medium such as water. For example, the component A can be obtained by using a latex or emulsion in which “other polymer” is dispersed in a medium such as water and mixing these latex or emulsion with a modified natural rubber latex. The latex or emulsion that can be used in the above method is preferably SBR latex, IR latex, NBR latex, MBR latex, BR latex, CR latex, AE emulsion or EVA emulsion, and particularly preferably SBR latex or AE emulsion.

  The A component requires that the A-1 component and the A-2 component are blended at a mass ratio (in terms of solid content) of 30:70 to 100: 0, and a mass of 60:40 to 100: 0. It is preferable to mix | blend by ratio (solid content conversion). By setting the mass ratio of the A-1 component and the A-2 component in the range of 30:70 to 100: 0, the adhesive composition has preferable characteristics of the modified natural rubber having strong self-adhesion and high rubber elasticity. It can be reliably applied to objects. On the other hand, in order to acquire the addition effect of A-2 component, it is preferable to mix | blend by mass ratio (solid content conversion) of 30: 70-95: 5.

[1-B] Amine (component B):
An amine is an essential component for suppressing yellowing of the coated body. In the present invention, the type of amine is not particularly limited, and a conventionally known amine can be used. For example, in addition to primary amines such as ethylamine, secondary amines such as diethylamine, tertiary amines such as triethylamine, and the like can be used.

  The amine may be an amine in which a substituted alkyl group is bonded to a nitrogen atom. The substituted alkyl group means an alkyl group in which part or all of the hydrogen atoms constituting the alkyl group are substituted with other substituents, and specific compounds include diisopropanolamine.

  Furthermore, the amine may be an amine in which a functional group other than an alkyl group is bonded to a nitrogen atom. That is, not only aliphatic amines such as ethylamine but also aromatic amines such as aniline, pyridine, piperidine, triethylenediamine (1,4-diazabicyclo [2.2.2] octane (hereinafter referred to as “DABCO”) and the like. The cyclic amine can also be suitably used as the component B. Furthermore, the amine may be not only a monoamine having one amino group but also a polyamine having a plurality of amino groups such as diamine and triamine. Specific examples of the compound include DABCO.

  The amine may be a liquid or a solid (powder, wax, etc.) at room temperature (25 ° C.). Examples of amines that are liquid at room temperature include triethylamine, dibutylamine, and diethanolamine. Examples of amines that are solid at room temperature include DABCO and diisopropanolamine. These amines may be used alone or in combination of two or more.

  As addition amount of B component, it is necessary to set it as 0.1-10 mass parts with respect to 100 mass parts (solid content conversion) of A component, and 0.5-2.5 mass parts It is preferable to be within the range. By making the addition amount of component B in the range of 0.1 to 10 parts by mass, the coating composition can be applied without deteriorating the original properties of the adhesive composition such as adhesive strength, rubber elasticity, film hardness, adhesive strength, and holding strength. The yellowing of the work body can be effectively suppressed. On the other hand, when the amount of component B added is less than 0.1 parts by mass, yellowing of the coated product may not be effectively suppressed. On the other hand, when the added amount of the component B exceeds 10 parts by mass, the original properties of the adhesive composition such as adhesive strength, rubber elasticity, film hardness, adhesive strength, and holding strength may be deteriorated.

[1-C] Silica (component C):
The adhesive composition of the present invention comprises the A component and the B component as essential components, but may further contain silica (C component). By blending silica, there is an advantage that an oil composition of the adhesive is improved, and an adhesive composition that exhibits a good adhesive force even on an adhesive surface with oil (machine oil or the like) can be obtained.

  As silica that can be used as component C, for example, powdery or particulate silica obtained by a conventionally known production method such as a wet method (precipitation method, gel method, etc.) or a dry method can be used.

  As addition amount of C component, it is preferable to set it as the range of 10-600 mass parts with respect to 100 mass parts (solid content conversion) of A component, and it is still more preferable to set it as the range of 30-200 mass parts. . By making the addition amount of C component in the range of 10 to 600 parts by mass, there is an advantage that the adsorptivity (oil absorption) such as machine oil can be improved without impairing the properties as an adhesive. . On the other hand, there exists a possibility that sufficient oil absorbency cannot be exhibited as the addition amount of C component is less than 10 mass parts. On the other hand, when the addition amount of C component exceeds 600 mass parts, adhesive force may fall.

  In producing the adhesive composition of the present invention, the A component (latex adhesive component), the B component (amine), and the C component (silica) are mixed in an arbitrary order so as to have a predetermined mixing ratio. do it. For example, after the A component and the B component are mixed in advance, the C component may be mixed with the mixture, or after the A component and the C component are mixed in advance, the B component may be mixed with the mixture. And after mixing B component and C component previously, you may mix A component with the mixture.

[1-D] Other additives:
The adhesive composition of the present invention may be formulated with additives other than the A component, the B component, and the C component depending on the purpose. That is, it may be a mixture of various additives such as those blended in conventionally known adhesive compositions. Examples of such additives include tackifiers, plasticizers, wetting agents, fillers, antioxidants, light stabilizers, UV absorbers, lubricants, flame retardants, pigments, dyes, antibacterial agents, stabilizers, and aging. Examples thereof include an inhibitor, a thickener, an antiseptic, and an antifoaming agent.

  Examples of the tackifier include terpene resins such as α-pinene resins, β-pinene resins, dipentene resins, and terpene phenol resins; natural rosins such as gums, woods, tall oils, and rosins. Modified rosin resins such as modified rosin resins modified with rosin derivatives; petroleum resins such as aliphatic petroleum resins, aromatic petroleum resins, alicyclic hydrogenated petroleum resins; and other coumarone-indene resins And polyolefin resins, polystyrene resins, phenol resins, xylene resins, and the like. Among them, rosin or rosin derivatives are stabilized by a modification means such as hydrogenation, disproportionation, and polymerization, and further modified rosin resins obtained by esterification with various polyalcohols such as glycerin and pentaerythritol (“polymerized rosin” Preferred are "esters".

  Examples of the plasticizer include dimethyl adipate, diisobutyl adipate, di- (2-ethylhexyl) adipate, diisooctyl adipate, diisodecyl adipate, octyldecyl adipate, di- (2-ethylhexyl) azelate, diisooctyl azelate, diisobutyl. Dibasic fatty acid esters such as azelate, dibutyl sebacate, di- (2-ethylhexyl) sebacate, diisooctyl sebacate; maleic acid ester; trimellitic acid isodecyl ester, trimellitic acid octyl ester, trimellitic acid n- Trimellitic acid esters such as octyl ester and isononyl trimellitic acid; epoxidized ester; trilauryl phosphate, tristearyl phosphate, tri- (2-ethylhexyl) phosphate Phosphate esters such as tricresyl phosphate; phosphonates; dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, butyl octyl phthalate, di- (2-ethylhexyl) phthalate, diisooctyl phthalate, diisodecyl phthalate, etc. Phthalic acid esters of polyhydric alcohols such as diethylene glycol monooleate. Among them, it is preferable to use at least one substance selected from the group consisting of dibasic fatty acid esters, maleic acid esters, trimellitic acid esters, adipic acid esters and polyhydric alcohol derivatives.

  Examples of the wetting agent include acetylene glycol, silicone, fluorine, fatty acid amide, and polyether wetting agents. By blending these wetting agents, the surface tension of the adhesive composition can be controlled, and an adhesive composition having an excellent balance between operability and adhesive force can be configured.

  As the filler, an organic filler or an inorganic filler can be used. The adhesive composition of the present invention is also preferably used as a pressure-sensitive adhesive, but is preferred because blocking of the coating layer (adhesive layer) formed when a filler is blended is preferred. Examples of the organic filler include polyethylene terephthalate resin beads, polybutylene terephthalate resin beads, polyamide resin beads, polycarbonate resin beads, polystyrene resin beads, polyimide resin beads, melamine resin beads, acrylic polymer resin beads, and polyvinyl acetate resin beads. Inorganic fillers that can include urea resin beads, polyvinyl ether resin beads, silicone-acrylic copolymer resin beads, powdered phenol resin beads, starch powder, etc. include, for example, calcium carbonate, magnesium carbonate, talc, mica, Examples thereof include aluminum hydroxide, magnesium hydroxide, kaolin clay, titanium oxide, zinc oxide, glass powder, and zeolite.

  Antioxidants such as phenols, organic phosphites, and thioethers as antioxidants, amides, organometallic salts, and esters as lubricants, and brominated organics as flame retardants. Flame retardants such as phosphoric acid, phosphoric acid, antimony trioxide, magnesium hydroxide, red phosphorus, organic pigments or inorganic pigments as pigments, and metal ion inorganic or organic antibacterial agents as antibacterial agents Can be mentioned.

  Moreover, as total solid content concentration of the adhesive composition of this invention, it is preferable that it is 10-85 mass%, and it is preferable that it is 15-60 mass%. When the total solid content concentration is less than 15 parts by mass, the workability may be deteriorated, for example, the coating property is deteriorated. On the other hand, if the total solid content concentration exceeds 85% by mass, the drying property may deteriorate, which is not practical.

[2] Method for suppressing yellowing of coated body:
As described above, the adhesive composition of the present invention has been described. However, an amine is not added to the adhesive composition, but an amine is added to the coating layer made of an adhesive composition containing no amine. The effect of suppressing yellowing of the coated body can also be enjoyed by coating or spraying.

  Specifically, on the surface of the base material, (A component): (A-1 component) natural rubber latex and (A-2 component) other polymer is a mass ratio (solid) of 30:70 to 100: 0. In a coated body formed with a coating layer made of a natural rubber-based adhesive composition containing a latex-like adhesive component blended in (part conversion), (B component): amine for the coating layer By coating or spreading, yellowing of the coated body can be suppressed. In the method of this invention, it is preferable to apply | coat or disperse | distribute B component within the range of 0.1-10 mass parts with respect to 100 mass parts of A component.

  Examples of the base material constituting the coated body include paper, synthetic paper, polyethylene, polyethylene terephthalate, polypropylene, resin films made of resins such as vinyl chloride, cloth, and wood panels.

  There is no restriction | limiting in particular about the method of forming a coating layer in the surface of a base material. For example, the adhesive composition is applied to the surface of the substrate by a conventionally known application means such as mechanical application such as gravure coater, air knife coater, or hand application such as brush, spray, bar coater, etc. What is necessary is just to form a coating layer.

  Hereinafter, the adhesive composition of the present invention will be described more specifically with reference to examples. However, these examples merely show some embodiments of the present invention. Accordingly, the present invention should not be construed as being limited to these examples.

(Example 1)
30 masses of methyl methacrylate (MMA, 100% solid content) as a vinyl monomer for modification with respect to 100 mass parts of solid content in natural rubber latex (Malaysia, high ammonia type natural rubber latex, solid content 61%) Partially polymerized to obtain a modified natural rubber latex.

  SBR latex so that the solid content of SBR latex (trade name: SBR0614, manufactured by JSR Corporation, 50% solid content) is 15 parts by mass with respect to 85 mass parts of solid content in the resulting modified natural rubber latex. Was added to prepare a latex adhesive component (component A).

Furthermore, with respect to 100 parts by mass of this A component, 0.5 parts by mass of triethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd., described as “Amine A” in Table 2) is added as a B component, whereby the solid content concentration A 50% composition was obtained. Furthermore, silica (trade name: Silica NIPGEL BY-001, manufactured by Tosoh Silica Co., Ltd., specific surface area 450 m ² / g, oil absorption 200 ml / 100 g) is used as component C with respect to 100 parts by mass of component A in the composition. The adhesive composition of Example 1 was obtained by adding 60 parts by mass.

(Comparative Example 1)
An adhesive composition of Comparative Example 1 was obtained in the same manner as Example 1 except that no B component was added.

(Examples 2-4, Comparative Examples 2-3)
Except having changed the quantity of triethylenediamine of B component, it carried out similarly to Example 1, and obtained the adhesive composition of Examples 2-4 and Comparative Examples 2-3.

(Example 5)
The adhesive composition of Example 5 was obtained in the same manner as in Example 2 except that the type of component B was changed from triethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd.) to diisopropanolamine (manufactured by Wako Pure Chemical Industries, Ltd.). .

(Example 6)
The adhesive composition of Example 6 was the same as Example 2 except that the type of component B was changed from triethylenediamine to triethylamine (manufactured by Wako Pure Chemical Industries, Ltd., described as “Amine C” in Table 2). Got.

(Comparative Example 4)
The adhesive composition of Comparative Example 4 was obtained in the same manner as Comparative Example 1 except that the acrylic copolymer was used alone without including any A-1 component (natural rubber latex) as the A component. . As the acrylic copolymer, an acrylate emulsion (AE, trade name: AE311, manufactured by JSR Corporation) was used.

[Evaluation methods]
About the adhesive composition of Examples 1-6 and Comparative Examples 1-4, yellowing degree, adhesive force, and film hardness were evaluated with the following method.

(1) Yellowing degree:
The adhesive compositions of Examples 1 to 6 and Comparative Examples 1 to 3 were coated on paper using a bar coater so that the coating amount was about 8.5 g / m ^2. The paper was dried with a 125 ° C. dryer for 25 seconds. Immediately after drying, the b ^* value was measured 15 times by the L ^* a ^* b ^* method using a color difference meter (trade name: Handy Color Difference Meter NR-3000, manufactured by Nippon Denshoku Industries Co., Ltd.).

After measuring the b ^* value, the coated body was immediately put in a plastic bag, and hermetically stored in a dark place at 30 ° C. for 3 days. After this sealed storage, the plastic bag was opened for 1 minute, and then the b ^* value was measured 15 times in the same manner as immediately after drying. The value obtained by subtracting the b ^* value immediately after drying from the b ^* value after opening (= Δb ^* value) was defined as the yellowing degree, and the yellowing degree was evaluated according to the criteria described in Table 1. The evaluation results are shown in Table 2.

(2) Adhesive strength:
Adhesive strength was measured as an index for evaluating the original properties of the adhesive composition. The adhesive compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were coated on paper using a bar coater so that the coating amount was about 8.5 g / m ^2. After drying for 60 seconds with a dryer at 0 ° C., curing was performed. The obtained coated body was cut into a size of 50 mm × 120 mm to obtain a test piece, which was superposed on the coated paper, and pressed and adhered. Then, the test piece was set to the tensile tester, and the load average value at the time of peeling in the 180 ° direction was measured. This test was performed 6 times, and the average value of the 6 measurements was taken as the adhesive strength, and the adhesive strength was evaluated according to the criteria described in Table 1. The evaluation results are shown in Table 2.

(3) Film hardness:
Film hardness was measured as an index for evaluating the original properties of the adhesive composition. A composition prepared by mixing only the A component and the B component in the blending amounts shown in Table 2 was prepared, and a film dried to a constant weight in a dryer at 35 ° C. was used. JIS K6253 “vulcanized rubber and thermoplastic The film hardness was measured based on the durometer hardness test described in “Rubber Hardness Test Method”, and the film hardness was evaluated according to the criteria described in Table 1. The evaluation results are shown in Table 2.

[Evaluation results]
As is apparent from the data in Table 2, the adhesive compositions of Examples 1 to 6 in which a predetermined amount of amine was blended were not only yellowing degree but also adhesive strength, film which is an original characteristic of the adhesive composition. Good results were shown in all evaluation items such as hardness. Especially, the adhesive composition of Example 2 and Example 5 which mix | blended 2 mass parts of triethylenediamine or diisopropanolamine showed the very favorable result in all the evaluation items.

  On the other hand, the adhesive composition of Comparative Example 1 in which no amine was blended and the adhesive composition of Comparative Example 2 in which the blending amount of amine was less than 0.1 parts by mass had a high degree of yellowing, and the coated body It was not possible to effectively suppress yellowing. Moreover, the adhesive composition of Comparative Example 3 in which the compounding amount of the amine was excessive was insufficient in the original properties of the adhesive composition such as adhesive strength and film hardness. Furthermore, the adhesive composition of Comparative Example 4 containing neither natural rubber nor modified natural rubber as the component A was insufficient in the original properties of the adhesive composition of adhesive strength and film hardness.

(Example 7)
Natural rubber latex (Malaysia, high ammonia type natural rubber latex, solid content 61%) is used as a latex-like adhesive component (component A). 0.2 parts by mass of ethylenediamine (manufactured by Wako Pure Chemical Industries, Ltd., described as “Amine A” in Table 2), polymerized rosin ester as a tackifier (trade name: Superester E-865NT, manufactured by Arakawa Chemical Industries) 20 parts by mass, 20 parts by mass of dibutyl adipate (Daihachi Chemical Co., Ltd.) as a plasticizer, and a polymer nonionic associative thickener (trade name: Adecanate UH420, manufactured by Asahi Denka Kogyo Co., Ltd.) 1 as a thickener The adhesive composition of Example 7 was obtained by adding .3 parts by mass and stirring for 30 minutes with a stirrer under normal temperature (25 ° C.) conditions.

(Comparative Example 5)
An adhesive composition of Comparative Example 5 was obtained in the same manner as in Example 7 except that no B component was added.

(Examples 8 to 10, Comparative Examples 6 to 7)
Except having changed the quantity of triethylenediamine of B component, it carried out similarly to Example 7, and obtained the adhesive composition of Examples 8-10 and Comparative Examples 6-7.

[Evaluation methods]
About the adhesive composition of Examples 7-10 and Comparative Examples 5-7, the adhesive tape was first manufactured with the following method.

  A film made of an olefin-based resin cut into a tape shape having a width of 250 mm is used as a base material, and the adhesive compositions of Examples 7 to 10 and Comparative Examples 5 to 7 are about 0.05 mm thick on one surface thereof. The film was dried at 100 ° C. for 3 minutes to form an adhesive layer having a thickness of about 0.03 mm, and this was wound to obtain a roll-shaped adhesive tape. At this time, a 0.02 μm-thick plastic film made of a resin obtained by combining a polypropylene copolymer resin and a polyethylene copolymer resin was used as a film serving as a base material.

  The pressure-sensitive adhesive tape thus obtained was evaluated by measuring the yellowing degree, the adhesive strength, and the holding power according to the following methods and standards.

(1) Yellowing degree:
The adhesive tape was dried for 25 seconds with a 125 ° C. dryer. Immediately after drying, the b ^* value was measured 15 times by the L ^* a ^* b ^* method using a color difference meter (trade name: Handy Color Difference Meter NR-3000, manufactured by Nippon Denshoku Industries Co., Ltd.).

After measuring the b ^* value, the adhesive tape was immediately put in a plastic bag and stored in a sealed place at 30 ° C. in the dark for 3 days. After this sealed storage, the plastic bag was opened for 1 minute, and then the b ^* value was measured 15 times in the same manner as immediately after drying. The value obtained by subtracting the b ^* value immediately after drying from the b ^* value after opening (= Δb ^* value) was defined as the degree of yellowing. The degree of yellowing was evaluated according to the criteria described in Table 3. The evaluation results are shown in Table 4.

(2) Adhesive strength:
About the obtained adhesive tape, based on the method (180 degree peeling method) as described in JIS Z0237, adhesive force was measured on conditions of 23 degreeC and 65% RH. Specifically, the obtained adhesive tape was attached to a test plate made of SUS304, and a 2 kg roller was reciprocated once to pressure-bond both, and left at 23 ° C. and 65% RH for 20 minutes. The adhesive force was measured under the condition of a peeling speed of 300 mm / min. The adhesive strength was evaluated according to the criteria described in Table 3. The evaluation results are shown in Table 4.

(3) Holding power:
About the obtained adhesive tape, the retention strength was measured based on the method of JISZ0237. Specifically, the obtained adhesive tape was attached to a test plate made of SUS304 so that the attachment area was 25 mm × 25 mm, and a 1 kg load was suspended in the vertical direction of the test plate. The deviation distance after the day was measured, and the value of the deviation distance was defined as the holding force. The holding power was evaluated according to the criteria described in Table 3. The evaluation results are shown in Table 4.

[Evaluation results]
As is apparent from the data in Table 4, the adhesive compositions of Examples 7 to 10 in which a predetermined amount of amine was blended, in addition to the yellowing degree, adhesive strength and retention which are the original characteristics of the adhesive composition Good results were shown in all evaluation items such as strength.

  On the other hand, the adhesive composition of Comparative Example 5 in which no amine was blended and the adhesive composition of Comparative Example 6 in which the blending amount of amine was less than 0.1 parts by mass had a high degree of yellowing, and the coated body It was not possible to effectively suppress yellowing. Moreover, the adhesive composition of Comparative Example 7 in which the compounding amount of the amine was excessive was insufficient in the inherent properties of the adhesive composition such as adhesive strength and holding power.

  The adhesive composition of the present invention can effectively suppress yellowing of the coated body without deteriorating the original properties of the adhesive composition such as adhesive strength, rubber elasticity, film hardness, adhesive strength, and holding power. Therefore, it can be suitably used for an adhesive composition containing silica having a large specific surface area or large oil absorption, or an adhesive composition based on paper. be able to.

Claims (4)

  (A component): (A-1 component) Latex in which natural rubber or modified natural rubber and (A-2 component) other polymer are blended at a mass ratio (in terms of solid content) of 30:70 to 100: 0 Adhesive component, and (B component): amine, the B component is blended within the range of 0.1 to 10 parts by mass with respect to 100 parts by mass (in terms of solid content) of the A component. A natural rubber adhesive composition. Furthermore, (C component): containing silica,
The adhesive composition according to claim 1, wherein the C component is blended within a range of 10 to 600 parts by mass with respect to 100 parts by mass of the A component. Mass ratio (solid content) of (A component) :( A-1 component) natural rubber or modified natural rubber latex and (A-2 component) other polymer on the surface of the substrate is 30:70 to 100: 0. In a coated body formed with a coating layer composed of a natural rubber-based adhesive composition containing a latex-like adhesive component formulated in terms of
(B component): A method of suppressing yellowing of the coated body by coating or spraying an amine on the coating layer.   The method according to claim 3, wherein the B component is applied or dispersed within a range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the A component.