Primer composition

Abstract

The present invention provides a primer composition that has excellent barrier properties and excellent jointability when used with pre-applied sealants. The primer composition contains (A) a film-forming component containing at least one selected from the group consisting of a polyisocyanate compound having three or more isocyanate groups, a polyester, a polyester polyurethane, an epoxy compound, and a chlorinated polymer, and (B) an alkoxysilyl group-containing methyl methacrylate polymer having a weight-average molecular weight of less than 15,000.

Description

[Technical Field]

[0001] The present invention relates to a primer composition. [Background technology]

[0002] Conventionally, in residential construction, a primer is applied to the surface of an exterior wall material before the sealant is applied to the surface. Applying a primer to the surface of the exterior wall material improves the adhesion between the adherend and the sealant, thereby strengthening the surface, which may have weak surface strength.

[0003] Furthermore, primer compositions are not simply secondary materials for sealants, but are also expected to play roles such as reducing the leaching of water, alkali, etc. from the adherend to the adhesive surface of the sealant, and reducing the migration of plasticizers, etc. from the adherend or sealant (see, for example, Non-Patent Document 1).

[0004] On the other hand, after a sealant has been applied to a surface or other application area, it may become necessary to repair the application area due to deterioration of the sealant. In this case, the existing sealant, i.e., the pre-applied sealant, is removed and a new sealant (post-applied sealant) is applied, but it may not be possible to completely remove the pre-applied sealant. In this case, the post-applied sealant must be applied over the pre-applied sealant. This joint application of sealants requires good adhesion between the pre-applied and post-applied sealants, but this adhesion often falls short of the desired target, and a primer is generally used for the joint application.

[0005] However, even if a primer is used when joining sealants, there are cases where the sealants are poorly joined or cannot be joined at all.

[0006] Therefore, there is known a primer composition for butt-jointing of a modified silicone-based sealing material, which contains: a) a polyisocyanate having an isocyanurate ring; b) an epoxy silane compound; c) one or more silane compounds selected from the group consisting of an amino silane compound having a structure represented by a predetermined formula, an amino silane compound having a structure represented by a predetermined formula, and a ketimine silane compound having a structure represented by a predetermined formula; and d) a film-forming resin, wherein the b) epoxy silane compound is at least one condensate of an epoxy silane represented by a predetermined formula, or a condensate of at least one epoxy silane represented by a predetermined formula and at least one alkoxy silane represented by a predetermined formula (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Non-Patent Documents

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, the primer composition for butt-jointing described in Patent Document 1 only exhibits butt-jointing properties by an amino silane, and does not satisfy the butt-jointing properties (normal adhesion, water-resistant adhesion, etc.) to the previously applied sealing material at a high level. Therefore, further improvement of these properties of the primer composition for butt-jointing is required. Furthermore, the primer composition is also required to have properties (hereinafter, in this specification, this property is referred to as "barrier property") for reducing the leaching of water, alkali, etc. from the inside of the porous material to the sealing material adhesion surface and reducing the transfer of plasticizers, etc. from the adherend and the sealing material.

[0010] Therefore, an object of the present invention is to provide a primer composition that has excellent barrier properties and also has excellent jointability when used with a pre-applied sealant. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a primer composition containing (A) a film-forming component including at least one selected from the group consisting of a polyisocyanate compound having three or more isocyanate groups, a polyester, a polyester polyurethane, an epoxy compound, and a chlorinated polymer, and (B) an alkoxysilyl group-containing methyl methacrylate polymer having a weight-average molecular weight of less than 15,000.

[0012] Furthermore, the above (B) is preferably an alkoxysilyl group-containing methyl methacrylate polymer containing an alkyl (meth)acrylate ester having an ester group with 8 or more carbon atoms.

[0013] The primer composition may further contain (C) an amino group-containing silane.

[0014] Furthermore, the primer composition may also contain (D) a silane-based crosslinking agent. [Effects of the Invention]

[0015] The primer composition of the present invention can provide a primer composition that has excellent barrier properties and also has excellent jointability when used with a pre-applied sealant. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Definitions and meanings of values ​​and terms> The definitions and meanings of terms used in this specification are as follows:

[0017] (Definition of room temperature) In this specification, "room temperature (normal temperature)" refers to a temperature of 23°C.

[0018] (Terminology: Solid at room temperature) As used herein, the term "solid at room temperature" means that the substance (e.g., a given composition) is crystalline, partially crystalline, and / or glassy amorphous and has a softening point (as measured by ring and ball method) or melting point greater than 23° C. The melting point is the temperature at which the material transitions from the solid to the liquid state, as measured, for example, by dynamic differential calorimetry (differential scanning calorimetry [DSC]) at the maximum of the curve during a heating operation.

[0019] (Weight average molecular weight) In this specification, the weight average molecular weight can be measured, for example, using a gel permeation chromatography (GPC) apparatus HLC-8220 (manufactured by Tosoh Corporation) under the following conditions using polystyrene as a standard substance.

[0020] Columns used: TSKgel SuperMultiporeHZ-M x 2, TSKguardcolumn SuperMP(HZ)-M x 1, TSKgel SuperMultiporeHM-L x 1 Solvent: THF Flow rate: 1.0ml / min Measurement temperature: 40℃

[0021] (glass transition temperature) The glass transition temperature (hereinafter sometimes referred to as "Tg") can be easily estimated from the type and amount of the monomer component using the following Fox equation.

[0022] 1 / Tg=W1 / Tg1+W2 / Tg2++W n / Tg n (Fox style)

[0023] In the above Fox formula, Tg is, for example, the glass transition temperature (K) of the acrylic resin, and W1, W2, ..., W nare the weight fractions of each monomer, and Tg1, Tg2, . . ., Tg n is the glass transition temperature of the homopolymer of each monomer. The glass transition temperature of the homopolymer used in the Fox equation can be a value listed in literature, such as Mitsubishi Rayon Co., Ltd.'s Acrylic Ester Catalog (1997 edition) or Kyozo Kitaoka, "New Polymer Library 7: Introduction to Synthetic Resins for Paints," Polymer Publishing Association, pp. 168-169.

[0024] <Outline of Primer Composition> The present inventors have conducted extensive research to improve the various properties required of a primer composition. As a result, they have discovered that the properties of a primer can be maximized by adding a predetermined film-forming component whose non-volatile components are solid to the primer composition. That is, they have found that a primer composition having excellent barrier properties and seamless application can be obtained by using a predetermined film-forming component and a silyl group-containing polymer.

[0025] That is, the primer composition according to the present invention is a composition containing (A) a film-forming component (hereinafter referred to as component (A)) and (B) an alkoxysilyl group-containing methyl methacrylate polymer (hereinafter referred to as component (B)). The primer composition according to the present invention may also contain (C) an amino group-containing silane (hereinafter referred to as component (C)), (D) a silane-based crosslinker (hereinafter referred to as component (D)), and / or other additives.

[0026] <Details of Primer Composition> The primer composition of the present invention contains (A) a film-forming component containing at least one compound selected from a predetermined group of compounds and (B) an alkoxysilyl group-containing methyl methacrylate polymer having a predetermined weight-average molecular weight. The primer composition of the present invention can also be prepared by adding components (C), (D), and / or other additives to components (A) and (B). The primer composition of the present invention exhibits moisture curing properties at room temperature.

[0027] <(A) Film-forming component> The film-forming component (A) contained in the primer composition of the present invention is not particularly limited as long as it is a component capable of forming a film that becomes a primer layer. Specifically, component (A) is a compound containing a solid component that is solid at room temperature. Examples of component (A) include film-forming resins such as polyisocyanate compounds having three or more isocyanate groups, polyesters, polyester polyurethanes, chlorinated polymers, and / or epoxy compounds. Among these, from the viewpoints of superior chemical resistance, hot water resistance, and excellent adhesion development (specifically, initial adhesion), it is preferable to include at least one compound selected from the group consisting of polyisocyanate compounds having three or more isocyanate groups, polyesters, polyester polyurethanes, chlorinated polymers, and epoxy compounds. These compounds can be used alone or in combination of two or more types.

[0028] The amount of component (A) added to the primer composition (based on solids content) is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, and preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. If the amount added to the primer composition exceeds 20%, the viscosity during application may increase, resulting in reduced workability. If the amount added is less than 1%, the primer composition may penetrate into the porous building material when applied to the porous building material, preventing it from exhibiting high film-forming properties. Note that this amount added is expressed as a percentage when the mass of the entire primer composition is taken as 100%.

[0029] [Polyisocyanate compound (A-1) having three or more isocyanate groups] As component (A) of the primer composition of the present invention, a polyisocyanate compound (A-1) having three or more isocyanate groups (hereinafter referred to as component (A-1)) can be used from the viewpoints of exhibiting high film-forming properties, increasing film strength after application, and improving adhesion to poorly adhesive painted surfaces. Furthermore, the isocyanate groups harden to exhibit excellent adhesion to substrates (siding boards, etc.), and crosslinking of the isocyanate groups can improve hot water-resistant adhesion and heat-resistant adhesion to substrates.

[0030] Examples of polyisocyanate compounds having three or more isocyanate groups include addition reaction products of diisocyanate compounds, such as adducts using trimethylolpropane, glycol, etc.; isocyanurate-modified polyisocyanates of diisocyanates; allophanate-modified polyisocyanates; biuret-modified polyisocyanates; etc. Such polyisocyanate compounds can be used alone or in combination of two or more.

[0031] Examples of the diisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), and polymethylene polyphenyl isocyanate (polymeric MDI); aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI); and alicyclic polyisocyanates such as isophorone diisocyanate (IPDI).

[0032] Examples of component (A-1) include polyisocyanate adducts obtained by reacting the above-mentioned polyisocyanate compounds (diisocyanate compounds) with compounds such as tris(phenylisocyanate)thiophosphate and trimethylolpropane (TMP), as well as adducts, biurets, and isocyanurates of polyisocyanate compounds. Hereinafter, such polyisocyanate compounds will be referred to as "isocyanate adducts." These compounds can be used alone or in combination of two or more.

[0033] Examples of such isocyanate adducts include an HDI-TMP adduct obtained by reacting HDI with TMP, an XDI-TMP adduct obtained by reacting XDI with TMP, a TDI-TMP adduct obtained by reacting TDI with TMP, a TMXDI-TMP adduct obtained by reacting TMXDI with TMP, an HXDI-TMP adduct obtained by reacting HXDI with TMP, an IPDI-TMP adduct obtained by reacting IPDI with TMP, a biuret of HDI, an isocyanurate of HDI, an isocyanurate of IPDI, an isocyanurate of TDI, etc. Among these, a TDI-TMP adduct obtained by reacting TDI with TMP and an isocyanurate-modified adduct are preferred.

[0034] The polyisocyanate compound having an isocyanurate ring is preferably an isocyanurate-modified diisocyanate compound obtained by trimerizing a diisocyanate compound. Examples of diisocyanate compounds include the aromatic polyisocyanates exemplified above. Among these, a polyisocyanate compound having an isocyanurate ring obtained by reacting a mixture of TDI and HDI is preferred from the viewpoint that it provides better initial adhesion and hot water-resistant adhesion to poorly adhesive coated surfaces, thereby providing sufficient adhesion.

[0035] (A-1) Examples of commercially available polyisocyanate compounds having three or more isocyanate groups include Takenate D-120N from Mitsui Chemicals, Inc., tris(phenylisocyanate) thiophosphate (Desmodur RFE) from Sumika Covestro Urethane Co., Ltd., a polyisocyanate compound having an isocyanurate ring obtained by reacting a mixture of HDI and TDI (Desmodur HL), and polymethylene polyphenylisocyanate (Sumidur 44V-10).

[0036] [Polyester (A-2)] The primer composition according to the present invention may contain (A-2) polyester (hereinafter referred to as component (A-2)) as component (A). The polyester as component (A-2) is not particularly limited. Examples of the polyester main chain include polyesters obtained by reacting carboxylic acids, including aromatic dicarboxylic acids and aliphatic dicarboxylic acids having 6 to 12 carbon atoms, with polyol compounds; and polyesters obtained by ring-opening polymerization of lactones such as polycaprolactone and polyvalerolactone.

[0037] The polyester has a main chain containing an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid having 6 to 12 carbon atoms as carboxylic acid components in the polyester skeleton, which provides excellent chemical and hot water resistance, excellent adhesion to poorly adhesive coated plates (especially water-resistant adhesion), and sufficient adhesion even when used in a low-temperature environment. The terminus of the polyester is not particularly limited. The polyester may be linear or branched.

[0038] Examples of aromatic dicarboxylic acids that can be used in producing polyester include phthalic acid (e.g., orthophthalic acid, phthalic anhydride), isophthalic acid, and terephthalic acid. These may be used alone or in combination of two or more. Among these, terephthalic acid and / or isophthalic acid are preferred from the viewpoints of excellent chemical resistance and hot water resistance, excellent adhesion to poorly adhesive coated plates, and sufficient adhesion even when used in a low-temperature environment.

[0039] Examples of aliphatic dicarboxylic acids having 6 to 12 carbon atoms that can be used in producing polyesters include adipic acid, azelaic acid, sebacic acid, and 1,12-dodecanedicarboxylic acid. These may be used alone or in combination of two or more. Among these, adipic acid and / or sebacic acid are preferred from the viewpoints of superior chemical resistance and hot water resistance, excellent adhesion to poorly adhesive coated plates, and sufficient adhesion even when used in a low-temperature environment. Sebacic acid is more preferred from the viewpoints of superior chemical resistance and hot water resistance, and rapid adhesiveness development, thereby ensuring sufficient adhesion even when used in a low-temperature environment.

[0040] The molar ratio of aromatic dicarboxylic acid to aliphatic dicarboxylic acid (aromatic dicarboxylic acid / aliphatic dicarboxylic acid) is preferably 1 / 99 to 99 / 1, and more preferably 5 / 95 to 95 / 5, from the viewpoints of providing excellent chemical resistance and hot water resistance, excellent adhesion to poorly adhesive coated plates, and sufficient adhesion even when used in a low-temperature environment.

[0041] The polyol compound that can be used when producing polyester is not particularly limited as long as it is a compound having two or more hydroxy groups. For example, polyol compounds commonly used in the production of polyester resins can be used. As the polyol compound, a compound having two hydroxy groups (i.e., a diol compound) is preferred. Examples include low-molecular-weight polyols such as ethylene glycol, propylene glycol, glycerin, hexanetriol, and trimethylolpropane; polyether-based polyols such as polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polyoxypropylene glycol, and polyoxybutylene glycol; polyolefin-based polyols such as polybutadiene polyol and polyisoprene polyol; adipate-based polyols; and lactone-based polyols. These may be used alone or in combination of two or more. Among these, ethylene glycol, propylene glycol, and neopentyl glycol are preferred from the viewpoint of excellent adhesiveness.

[0042] The number average molecular weight of the polyester is preferably 3,000 or more, more preferably 15,000 or more, and preferably 70,000 or less, from the viewpoints of excellent chemical resistance, excellent adhesion to poorly adhesive coated boards, and sufficient adhesion even when used in low-temperature environments. Furthermore, from the viewpoint of excellent chemical resistance, excellent hot water resistance, the number average molecular weight of the polyester is preferably 15,000 or more, more preferably 15,000 or more and 70,000 or less. The number average molecular weight of the polyester is the molecular weight expressed in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0043] The method for producing the polyester is not particularly limited. For example, a conventionally known method for producing polyester can be used. The multiple types of polyester can be used alone or in combination of two or more.

[0044] [Polyester polyurethane (A-3)] The primer composition according to the present invention may contain (A-3) polyester polyurethane (hereinafter referred to as component (A-3)) as component (A). There are no particular limitations on the (A-3) polyester polyurethane that can be used as the film-forming component in the primer composition of the present invention. For example, there may be mentioned compounds obtained by urethane-modifying the above polyesters having two or more hydroxy groups with a polyisocyanate compound (a bifunctional or higher isocyanate compound). There are also no particular limitations on the main chain (polyester portion) of the polyester polyurethane. For example, there may be mentioned main chains similar to those of the above polyesters. Furthermore, the polyester polyurethane may be either linear or branched.

[0045] From the viewpoint of achieving superior chemical resistance and hot water resistance, the number average molecular weight of the polyester polyurethane is preferably 10,000 or more, more preferably 15,000 or more, and is preferably 100,000 or less, more preferably 70,000 or less. The number average molecular weight of the polyester polyurethane is the molecular weight expressed in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0046] Here, examples of the urethane modification method include dissolving a polyester having two or more hydroxy groups in an organic solvent that does not react with a polyisocyanate compound, adding the polyisocyanate compound thereto, and optionally adding a reaction catalyst such as an amine compound or an organometallic compound, followed by heating.

[0047] In addition, examples of polyesters having two or more hydroxy groups used in the production of polyester polyurethane include the polyesters described above. Two or more of these may be used in combination.

[0048] The polyisocyanate compound used in producing the polyester polyurethane may be, for example, an alicyclic, aromatic, or aliphatic diisocyanate compound, i.e., any of the diisocyanate compounds listed in the description of component (A-1).

[0049] In addition, the polyisocyanate compound may be an isocyanate compound having three or more functionalities, such as an adduct, an isocyanurate, or a biuret. As the polyisocyanate compound used in producing polyester polyurethane, it is preferable to use a diisocyanate compound, as it is less likely to gel.

[0050] The method for producing polyester polyurethane is not particularly limited. For example, a conventionally known method for producing polyester polyurethane can be used. Suitable commercially available polyester polyurethane products include Nipporan 3024 manufactured by Tosoh Corporation and Pandex T-5205 and Pandex T-5210 manufactured by DIC Corporation. The multiple types of polyester polyurethane can be used alone or in combination of two or more.

[0051] [Epoxy compound (A-4)] The primer composition according to the present invention may contain (A-4) an epoxy compound (hereinafter referred to as component (A-4)) as component (A). The epoxy compound reacts with (C) an amino group-containing silane to strengthen the network structure obtained after the primer composition is cured, thereby improving adhesion, water-resistant adhesion, and adhesion durability under high-temperature and high-humidity conditions. The strong network structure also enhances barrier performance, preventing discoloration and deterioration of the sealant-bonded portion of the adherend and its surrounding area. In particular, the epoxy compound reacts with compounds having reactive groups to inhibit migration of the active compounds, thereby exhibiting excellent effectiveness in preventing discoloration and deterioration caused by compounds having reactive groups reactive to epoxy groups, such as amine compounds.

[0052] Examples of the epoxy compound include aromatic, aliphatic, and alicyclic epoxy compounds that are solid at room temperature. Examples of the aromatic epoxy compound include bisphenol A epoxy compounds, bisphenol F epoxy compounds, bisphenol AD ​​epoxy compounds, bisphenol S epoxy compounds, naphthalene epoxy compounds, phenol novolac epoxy compounds, cresol novolac epoxy compounds, and polyfunctional epoxy compounds.

[0053] Examples of the alicyclic epoxy compounds include hydrogenated aromatic epoxy compounds, cyclohexane-based, cyclohexyl methyl ester-based, cyclohexyl methyl ether-based, spiro-based, and tricyclodecane-based epoxy compounds. Specific examples include hydrogenated bisphenol A-based epoxy compounds; 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1,2:8,9-diepoxylimonene, 1,2-epoxy-4-vinylcyclohexane, and 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (EHPE3150, manufactured by Daicel Corporation).

[0054] Among the epoxy compounds, bisphenol A type epoxy resins and alicyclic epoxy compounds that are solid at room temperature are preferred from the viewpoint of being able to obtain a primer that has excellent jointability when used with pre-applied sealants.

[0055] [Chlorinated polymer (A-5)] The primer composition according to the present invention may contain (A-5) a chlorinated polymer (hereinafter referred to as component (A-5)) as component (A). The (A-5) chlorinated polymer is not particularly limited as long as it is a compound obtained by chlorinating natural rubber, synthetic rubber, polyolefin, or a modified product thereof (hereinafter, natural rubber, synthetic rubber, polyolefin, and a modified product thereof are also collectively referred to as "polymer").

[0056] As component (A-5), chlorinated natural rubber and chlorinated synthetic rubber are preferred from the viewpoint of providing a composition with superior adhesion to difficult-to-adhere materials, and a primer with excellent jointability can be obtained, particularly when used with pre-applied sealants. Furthermore, the use of chlorinated polyisoprene is more preferred from the viewpoint of providing a composition with excellent application workability due to its low viscosity, and particularly excellent adhesion to difficult-to-adhere materials.

[0057] Examples of synthetic rubbers include polyisoprene, styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), etc. Examples of polyolefins include polyethylene, polypropylene, etc.

[0058] From the viewpoint of excellent adhesiveness to hard-to-adhere materials, the weight-average molecular weight of component (A-5) is preferably 50,000 or more and 300,000 or less. From the viewpoint of even more excellent adhesiveness, the weight-average molecular weight of component (A-5) is more preferably 60,000 or more, even more preferably 70,000 or more, more preferably 280,000 or less, even more preferably 260,000 or less.

[0059] From the viewpoint of excellent adhesiveness, the chlorine content of component (A-5) is preferably 40% by mass or more and 80% by mass or less. From the viewpoint of even more excellent adhesiveness, the chlorine content of component (A-5) is more preferably 45% by mass or more, even more preferably 50% by mass or more, and even more preferably 80% by mass or less. The chlorine content of component (A-5) refers to the proportion of chlorine atoms in component (A-5).

[0060] <(B) Alkoxysilyl Group-Containing Methyl Methacrylate Polymer> The (B) alkoxysilyl group-containing methyl methacrylate polymer is a (meth)acrylic ester polymer having an alkoxysilyl group and containing methyl methacrylate, which is solid at room temperature, as an essential monomer. The (B) alkoxysilyl group-containing methyl methacrylate polymer according to the present invention is preferably a resin having a weight-average molecular weight of less than 15,000.

[0061] Component (B) allows the primer composition to exhibit excellent adhesion to the cured sealant (pre-applied sealant) and achieve good jointability. Furthermore, when component (B) is used in combination with component (C), described below, even better adhesion to the cured sealant (pre-applied sealant) and good jointability are achieved. Furthermore, the alkoxysilyl groups of component (B) and the alkoxysilyl groups of component (C), described below, harden, resulting in excellent adhesion to substrates (siding boards, etc.). Furthermore, crosslinking between the silyl groups of component (B) and component (C) improves hot water-resistant adhesion to substrates.

[0062] (alkoxysilyl group) The alkoxysilyl group of component (B) has an alkoxy group bonded to a silicon atom and is capable of crosslinking by a silanol condensation reaction. Examples of the alkoxysilyl group include groups represented by the following general formula (1):

[0063] [ka]

[0064] In general formula (1), R 1 represents an alkyl group having 1 to 20 carbon atoms, a substituted alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms; R 1 When two or more X's are present, they may be the same or different. X represents an alkoxysilyl group, and when two or more X's are present, they may be the same or different. a represents 0, 1, 2, or 3. In the alkoxysilyl group of general formula (1), it is preferable that a is 2 or 3. When a is 3, the curing rate is higher than when a is 2.

[0065] R 1Specific examples of the alkyl group include alkyl groups such as methyl and ethyl groups, substituted alkyl groups such as methoxymethyl groups, and cycloalkyl groups such as cyclohexyl groups. Of these, methyl groups are preferred, and from the viewpoint of increasing the curing rate, substituted alkyl groups in which the α-carbon is substituted with a polar group are preferred.

[0066] The alkoxysilyl group represented by X is not particularly limited, and may be any conventionally known alkoxysilyl group. Among alkoxy groups, groups with fewer carbon atoms have higher reactivity, and the reactivity decreases as the number of carbon atoms increases, in the order of methoxy group > ethoxy group > propoxy group. While it can be selected depending on the purpose and application, methoxy group or ethoxy group is usually used. In the case of an alkoxysilyl group represented by general formula (1), a is preferably 2 or more in consideration of curability.

[0067] Specifically, examples of the alkoxysilyl group include trialkoxysilyl groups (-Si(OR)), such as trimethoxysilyl and triethoxysilyl groups. 2 ) 3); Dialkoxysilyl groups (-SiR) such as methyldimethoxysilyl group and methyldiethoxysilyl group 1 (OR 2 )2) where R 1 is the same as above, and R 2 is an alkyl group such as a methyl group or an ethyl group. As the alkoxysilyl group, a trimethoxysilyl group or a triethoxysilyl group is preferred from the viewpoint of high reactivity, and a trimethoxysilyl group is more preferred. From the viewpoint of obtaining a flexible cured product, a methyldimethoxysilyl group or a methyldiethoxysilyl group is preferred.

[0068] The alkoxysilyl group may be used alone or in combination of two or more types. The alkoxysilyl group may be present in the main chain, the side chain, or both.

[0069] The number (average) of alkoxysilyl groups in component (B) per polymer molecule is preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 1 or more, and is preferably 5 or less, more preferably 3 or less, and even more preferably 2.5 or less. If the number of alkoxysilyl groups contained in the molecule is less than 0.3, curability will be insufficient, and if it is too many, the network structure will be too dense and will not exhibit good mechanical properties.

[0070] (Method for introducing alkoxysilyl groups) In preparing component (B), various known methods can be used to introduce alkoxysilyl groups into the (meth)acrylic acid ester polymer. For example, the following method can be mentioned as an example of a method for introducing alkoxysilyl groups.

[0071] (1) Copolymerizing an unsaturated compound having an alkoxysilyl group. (2) Polymerization is carried out using an initiator or chain transfer agent having an alkoxysilyl group. (3) A (meth)acrylic acid ester polymer having a functional group such as a hydroxyl group is reacted with a compound having an alkoxysilyl group and another functional group capable of reacting with the functional group, such as an epoxysilane.

[0072] Among these methods for introducing alkoxysilyl groups, (1) copolymerization of an unsaturated compound having an alkoxysilyl group is preferred from the viewpoint of ease of introduction of the alkoxysilyl group. A combination of methods (1) and (2) is also preferred. For example, a trimethoxysilyl group-containing (meth)acrylic polymer can be obtained as an alkoxysilyl group-containing methyl methacrylate polymer by using methyl methacrylate, 2-ethylhexyl methacrylate, 3-methacryloxypropyltrimethoxysilane, titanocene dichloride as a metal catalyst, 3-mercaptopropyltrimethoxysilane (which acts as an initiator and also as a chain transfer agent due to the action of titanocene dichloride), and a benzoquinone solution as a polymerization terminator in accordance with Synthesis Example 4 of WO2015-088021.

[0073] (Unsaturated compounds having an alkoxysilyl group) The unsaturated compound having an alkoxysilyl group used in copolymerization is preferably a (meth)acrylic acid alkyl ester or vinylsilane having an alkoxysilyl group. Examples of such compounds include 3-(meth)acryloxypropyl alkoxysilanes such as 3-(meth)acryloxypropyl trimethoxysilane, 3-(meth)acryloxypropyl methyldimethoxysilane, and 3-(meth)acryloxypropyl triethoxysilane, and vinyl alkoxysilanes such as vinyl triethoxysilane. Among these, a (meth)acrylic acid alkyl ester having a substituted alkyl group in which the alkyl group having an alkoxysilyl group has 10 or less carbon atoms, preferably 3 or less carbon atoms, is preferred.

[0074] (Monomers other than the monomer having an alkoxysilyl group used in component (B)) Examples of other monomers, excluding the monomer having an alkoxysilyl group, used in the synthesis of the polymer of component (B) according to the present invention include methyl methacrylate random copolymers having a repeating unit represented by general formula (2) in which methyl methacrylate is an essential monomer component.

[0075] -CH2C(R 3 )(COOR 4 )- (2)

[0076] In general formula (2), R 3 is a hydrogen atom or a methyl group, R 4 represents a hydrocarbon group which may have a substituent. The (meth)acrylic acid ester represents an acrylic acid ester and / or an alkyl methacrylic acid ester.

[0077] As the monomer having an alkoxysilyl group and the other monomer other than methyl methacrylate used in the synthesis of the polymer of component (B) according to the present invention, a (meth)acrylic acid alkyl ester is preferred, a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 30 carbon atoms is more preferred, and a (meth)acrylic acid alkyl ester having an alkyl group with 1 to 30 carbon atoms and no substituent is particularly preferred.

[0078] Examples of the (meth)acrylic acid alkyl ester compound include known compounds, such as methyl acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate.

[0079] Furthermore, from the viewpoint of achieving excellent adhesion to the cured sealant (pre-applied sealant) and good jointability, (meth)acrylic acid alkyl esters having an ester group with 8 or more carbon atoms, such as 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate, are preferred. From the viewpoint of imparting flexibility to component (B), it is preferable to use (meth)acrylic acid alkyl esters with a glass transition temperature (Tg) of 0°C or less, such as n-butyl acrylate (Tg; -55°C), 2-ethylhexyl acrylate (Tg; -70°C), and lauryl acrylate (Tg; -3°C). Note that the glass transition temperature in this paragraph refers to the glass transition temperature of the homopolymer.

[0080] The hydrocarbon group, such as the alkyl group, of the (meth)acrylic acid ester may have a substituent, such as a hydroxyl group, an alkoxy group, a halogen atom, or an epoxy group. Examples of such compounds include (meth)acrylic acid esters having a hydroxyl group, such as hydroxyethyl (meth)acrylate, (meth)acrylic acid esters having an alkoxy group, such as methoxyethyl (meth)acrylate, (meth)acrylic acid esters having an epoxy group, such as glycidyl (meth)acrylate, and (meth)acrylic acid esters having an amino group, such as diethylaminoethyl (meth)acrylate. It is also possible to use unsaturated compounds (macromonomers or macromers) having a polymer chain, such as acrylic acid esters having a polystyrene chain.

[0081] Furthermore, the alkoxysilyl group-containing methyl methacrylate polymer of component (B) may contain, in addition to the repeating units derived from the (meth)acrylic acid ester compound, repeating units derived from a compound copolymerizable therewith. Examples of compounds copolymerizable with the (meth)acrylic acid ester compound include acrylic acids such as (meth)acrylic acid; amide compounds such as (meth)acrylamide; vinyl ether compounds such as alkyl vinyl ether; and others such as acrylonitrile, styrene, α-methylstyrene, vinyl chloride, and vinyl acetate.

[0082] (Monomer usage ratio) The amount of methyl methacrylate in the polymer of component (B) is less than 80% by weight, preferably 20% by weight or more, more preferably 30% by weight or more, and even more preferably 40% by weight or more. The amount of the compound copolymerizable with the (meth)acrylic acid ester compound in the polymer of component (B) is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 5% by weight or less. However, when a macromonomer is used, the amount of the macromonomer in the polymer of component (B) is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less.

[0083] (glass transition temperature) Component (B) has a glass transition temperature (Tg) of 0°C or higher and 120°C or lower. The glass transition temperature is preferably 0°C or higher, more preferably 20°C or higher, and even more preferably 40°C or higher. It is also preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower. If the glass transition temperature is lower than 0°C, the adhesive strength immediately after bonding tends to be poor. If the glass transition temperature exceeds 120°C, the viscosity increases, making it difficult to apply the primer to the adherend. The glass transition temperature can be easily estimated using the Fox equation described above.

[0084] The molecular weight of component (B) is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and is preferably less than 15,000, more preferably 10,000 or less, and even more preferably 6,000 or less, in terms of weight average molecular weight (molecular weight measured in terms of polystyrene by GPC). If the weight average molecular weight is less than 1,000, the initial adhesive strength after application is low, and if it exceeds 20,000, the viscosity during application becomes too high, reducing workability. It is also preferable that the polymer of component (B) is solid at room temperature or has a ring and ball softening point of 80°C or higher.

[0085] The amount of component (B) added to the primer composition is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, and preferably 60% or less, more preferably 50% or less, and even more preferably 40% or less. If the amount added exceeds 60%, the viscosity during application becomes too high, reducing workability, while if it is less than 5%, good jointability cannot be achieved. Note that this amount added is expressed as a percentage when the mass of the entire primer composition is taken as 100%.

[0086] (Polymerization method of component (B)) Radical polymerization can be used as the polymerization method for component (B). For example, conventional solution polymerization or bulk polymerization methods using thermal polymerization initiators such as benzoyl peroxide or azobisisobutyronitrile can be used. Polymerization methods using a photopolymerization initiator and irradiation with light or radiation can also be used. In radical copolymerization, chain transfer agents such as lauryl mercaptan or 3-mercaptopropyltrimethoxysilane can be used to adjust the molecular weight. Radical polymerization methods using thermal polymerization initiators can also be used, and such methods can easily produce the polymer of component (B) according to the present invention. Other polymerization methods, such as living radical polymerization as described in JP 2000-086998 A, can also be used.

[0087] <(C) Amino group-containing silane> From the viewpoint of not only improving adhesion to substrates (adhesive members) but also further improving adhesion to cured sealant products (pre-applied sealant) when used in combination with component (B) and achieving excellent jointability, the primer composition of the present invention preferably further contains (C) an amino group-containing silane. Examples of the amino group of the (C) amino group-containing silane include monovalent functional groups formed by removing hydrogen from primary or secondary amines and ketimine groups. Specific examples of the (C) amino group-containing silane of the present invention include aminosilanes and ketimine silanes. Ketimine silanes are silane compounds that generate a specific amine upon reaction with moisture, and in the present invention, ketimine silanes are also included in component (C).

[0088] Examples of aminosilanes include mono-silylaminosilanes such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(β-aminoethyl)-3-aminopropyltrimethoxysilane, N-(β-aminoethyl)-3-aminopropyltriethoxysilane, and N-(β-aminoethyl)-3-aminopropylmethyldiethoxysilane; and bis-silylaminosilanes such as bis-(trimethoxysilylpropyl)amine, bis-(triethoxysilylpropyl)amine, bis-(triethoxysilylpropyl)ethylenediamine, N-[2-(vinylbenzylamino)ethyl]-3-aminopropyltrimethoxysilane, and aminoethyl-aminopropyltrimethoxysilane.

[0089] Further examples of the aminosilane include aminosilane reactants such as the reaction product of the above aminosilane with an epoxysilane, the reaction product of an aminosilane with a silane having a (meth)acryloyloxy group, the reaction product of an aminosilane with an epoxy resin (bisphenol A diglycidyl ether, phenyl glycidyl ether, etc.), and the reaction product of an aminosilane with a polyacrylate; condensates obtained by partially condensing the above silanes (preferably aminosilane condensates obtained by partially condensing the above aminosilane, aminosilane reactant, and a mixture of the reactants); and modified derivatives thereof.

[0090] Examples of ketimine silanes include N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(methyldimethoxysilyl)-1-propanamine, and N-(1,3-dimethylbutylidene)-3-(methyldiethoxysilyl)-1-propanamine.

[0091] The amount of component (C) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of components (A) and (B). The amount of component (B) refers to the amount of solids in component (B) excluding the solvent component.

[0092] <(D) Silane-based crosslinking agent> The primer composition according to the present invention may further contain (D) a silane-based crosslinking agent. Examples of (D) silane-based crosslinking agents include silane compounds having two or more alkoxysilyl groups, excluding component (C). (D) silane-based crosslinking agent strengthens the network structure obtained after the primer composition is cured, thereby improving adhesion, water-resistant adhesion, and adhesion durability under high-temperature and high-humidity conditions. (D) silane-based crosslinking agent can also improve the barrier properties of the primer composition by promoting crosslinking. Therefore, from the viewpoint of improving crosslink density, the number of alkoxysilyl groups in component (D) is preferably two or more, more preferably three or more.

[0093] As component (D), isocyanurate silane, carbasilatrane, silane reactant, silane condensate, etc. can be used.

[0094] Examples of isocyanurate silanes include tris-(trimethoxysilylpropyl) isocyanurate, etc. Examples of carbasilatranes include 1.0 mol of 3-aminopropyltrimethoxysilane and 3-glycidoxypropyltrimethysilane as described in Japanese Patent No. 3831481. Examples include a reaction product of 2.0 moles of xysilane.

[0095] Examples of the silane reactants and silane condensates (however, in this paragraph, compounds containing a primary amino group or a secondary amino group are excluded) include aminosilane reactants such as a reaction product of an aminosilane with an epoxy silane, a reaction product of an aminosilane with an isocyanate silane, a reaction product of an aminosilane with a silane having a (meth)acryloyloxy group, a reaction product of an aminosilane with an epoxy resin (bisphenol A diglycidyl ether, phenyl glycidyl ether, etc.), a reaction product of an aminosilane with a polyisocyanate, and a reaction product of an aminosilane with a polyacrylate; condensates obtained by partially condensing the above-mentioned silanes (preferably aminosilane condensates obtained by partially condensing the above-mentioned aminosilane, isocyanate silane, aminosilane reactant, and a mixture of the reactants); and modified derivatives thereof, such as amino-modified silyl polymers and silylated amino polymers.

[0096] When component (D) is used, the amount of the silane crosslinking agent (D) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the total amount of components (A) and (B), and is preferably 60 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 15 parts by mass or less. The amount of component (B) refers to the amount of solids in component (B) excluding the solvent component.

[0097] <Other additives> The primer composition of the present invention may contain other additives as needed, such as a methyl methacrylate polymer, a solvent, a condensation reaction-accelerating catalyst, a dehydrating agent, a silane adhesion promoter, a polyisocyanate compound (diisocyanate compound), a pigment, a dye, an antioxidant, an antistatic agent, and a flame retardant.

[0098] (methyl methacrylate polymer) As the methyl methacrylate polymer, a resin that is solid at room temperature and contains 80% by weight or more of methyl methacrylate and has a weight average molecular weight Mw (apparent weight average molecular weight converted into polymethyl methacrylate by GPC method) of 60,000 or more is preferred.

[0099] By making the proportion of methyl methacrylate in the resin 80% by weight or more and the weight-average molecular weight 60,000 or more, when the primer composition according to the present invention is applied to a porous building material, the penetration of the primer composition into the porous building material can be further suppressed. As a result, the primer composition according to the present invention can exhibit better film-forming properties, and the film strength after application is stronger, exhibiting better adhesion.

[0100] The resin includes a homopolymer of methyl methacrylate, or a copolymer of methyl methacrylate with one or more copolymerizable monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, acrylonitrile, acrylic acid, methacrylic acid, 2-hydroxyacrylate, maleic anhydride, styrene, or α-methylstyrene.

[0101] Copolymerizable monomers are preferably alkyl acrylates in which the alkyl group has 1 to 4 carbon atoms, such as methyl acrylate, ethyl acrylate, and n-butyl acrylate, and (meth)acrylic acid, with methyl acrylate, ethyl acrylate, and (meth)acrylic acid being more preferred, and methyl acrylate and (meth)acrylic acid being even more preferred. Copolymerization of methyl methacrylate with these monomers increases the solubility of the methyl methacrylate polymer in solvents, and also allows the viscosity of the primer composition according to the present invention to be adjusted to an appropriate viscosity (thickening), making it less likely to penetrate porous building materials. Therefore, the primer composition according to the present invention can exhibit better film-forming properties, stronger film strength after application, and superior adhesion.

[0102] Commercially available methyl methacrylate polymers include, for example, Delpowder (registered trademark) 80N, a copolymer with methyl acrylate (manufactured by Asahi Chemical Industry Co., Ltd., polymethyl methacrylate, methyl methacrylate / methyl acrylate weight ratio of 97.5 / 2.5, weight average molecular weight of 100,000, reduced viscosity of 0.54 dL / g, glass transition temperature of 105°C), and Dianale (registered trademark) BR-84, a copolymer with (meth)acrylic acid (manufactured by Mitsubishi Rayon Co., Ltd., polymethyl methacrylate, weight average molecular weight of 100,000, glass transition temperature of 105°C, acid value: 6.5 mgKOH / g).

[0103] The weight-average molecular weight Mw of the methyl methacrylate polymer is preferably 60,000 or more, more preferably 70,000 or more, even more preferably 80,000 or more, and particularly preferably 90,000 or more. The weight-average molecular weight Mw of the methyl methacrylate polymer is typically preferably 200,000 or less, more preferably 180,000 or less, even more preferably 160,000 or less, and particularly preferably 140,000 or less. When the weight-average molecular weight Mw of the methyl methacrylate polymer is 60,000 or more, the barrier properties, adhesion durability, and adhesion to porous surfaces of the primer composition can be further improved. When the weight-average molecular weight Mw is 200,000 or less, the primer composition can achieve better adhesion durability, better workability, and higher adhesion to porous surfaces.

[0104] The proportion of methyl methacrylate contained in the methyl methacrylate polymer is preferably 80% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more. The glass transition temperature of the methyl methacrylate polymer is preferably 80°C or more, more preferably 90°C or more, and even more preferably 95°C or more, and is preferably 140°C or less, more preferably 120°C or less, and even more preferably 110°C or less.

[0105] The amount of methyl methacrylate polymer added to the primer composition is preferably 1% or more, more preferably 2% or more, even more preferably 3% or more, and preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. If the amount added to the primer composition exceeds 20%, the viscosity during application may increase, resulting in reduced workability. If the amount added is less than 1%, the primer composition may penetrate into the porous building material when applied to the porous building material, preventing it from exhibiting high film-forming properties. Note that this amount added is expressed as a percentage when the mass of the entire primer composition is taken as 100%.

[0106] (solvent) Examples of the solvent include organic solvents such as aliphatic compounds (n-hexane, heptane, etc.), aromatic compounds (toluene, xylene, etc.), alcohols (methanol, ethanol, isopropyl alcohol, butanol, etc.), ketones (acetone, methyl ethyl ketone, etc.), esters (ethyl acetate, butyl acetate, etc.), ethers (tetrahydrofuran, butyl cellosolve, etc.), ligroin, etc. One or more of these solvents can be used, and an appropriate amount can be added to the primer composition according to the present invention.

[0107] Among these solvents, methyl ethyl ketone and ethyl acetate are preferred from the viewpoint of improving adhesion speed and workability. It is preferable to thoroughly dry or dehydrate the above solvents before use.

[0108] The content of the solvent is preferably 40% to 90% and more preferably 50% to 80% based on the total mass of the primer composition of the present invention. If the content of the solvent is within this range, good coating properties can be obtained. The content of the solvent in the primer composition of the present invention can be changed as appropriate depending on the use, purpose, etc. of the composition.

[0109] (Condensation reaction accelerator) As the catalyst for promoting the condensation reaction of the alkoxysilyl group, a wide variety of known curing catalysts can be used, and it is preferable to use, for example, a silanol condensation catalyst. Examples of the silanol condensation catalyst include metal catalysts, tin catalysts, and amine catalysts, and examples of the amine catalyst include organometallic compounds, amines (particularly tertiary amines), and salts of tertiary amines with carboxylic acids, etc.

[0110] Specific examples of organometallic compounds include divalent organotin compounds such as tin octoate; tetravalent organotin compounds such as dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, and reaction products of dibutyltin oxide with phthalic acid esters; chelate compounds of various metals such as dibutyltin bis(acetylacetonate), titanium tetrakis(acetylacetonate), aluminum tris(acetylacetonate), and acetylacetonate bismuth; and titanate esters such as tetrapropyl titanate.

[0111] Examples of amines include primary and secondary amines such as octylamine, polyamines, cyclic amines such as N-methylmorpholine and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU), amine compounds such as aminophenol compounds such as 2,4,6-tris(dimethylaminomethyl)phenol, and carboxylate salts thereof, and reaction products of excess polyamines and epoxy compounds. These catalysts can be used alone or in combination of two or more.

[0112] Among these, tin-based catalysts and amine-based catalysts are preferred, and tin-based catalysts are particularly preferred, from the viewpoint of having high catalytic activity even in small amounts. Either one or both of the tin-based catalyst and the amine-based catalyst may be used. As the tin-based catalyst, either a divalent or tetravalent tin catalyst may be used alone, or both may be used in combination. As the amine-based catalyst, tertiary amines are preferably used.

[0113] When a condensation reaction-promoting catalyst is used, the amount of the condensation reaction-promoting catalyst is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, relative to 100 parts by mass of the total amount of component (A) and component (B); and is preferably 10 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less.

[0114] (dehydrating agent) Examples of the dehydrating agent include silane compounds such as vinyltrimethoxysilane, dimethoxydiphenylsilane, methyltrimethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, and tetramethoxysilane; and ester compounds such as methyl orthoformate and ethyl orthoformate. These dehydrating agents can be used alone or in combination of two or more. Note that silane compounds are preferred as the dehydrating agent, and dimethoxydiphenylsilane and phenyltrimethoxysilane are more preferred.

[0115] When a dehydrating agent is used, the amount of the dehydrating agent is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of component (A) and component (B); and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less.

[0116] (Silane adhesion promoter) Silane adhesion promoters can be added to the primer composition of the present invention because they are effective in improving adhesion to poorly adherent coated surfaces. Examples of silane adhesion promoters include epoxy silanes, acrylic silanes, mercapto silanes, urea silane coupling agents, and isocyanate silanes.

[0117] Examples of epoxy silanes include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane. Examples of acrylic silanes include 3-methacryloxypropyltrimethoxysilane. Examples of mercaptosilanes include 3-mercaptopropyltrimethoxysilane. Examples of urea silane coupling agents include 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane. Examples of isocyanate silanes include 3-isocyanatepropyltriethoxysilane.

[0118] From the viewpoint of adhesiveness, epoxy silane, acrylic silane-based silane, urea silane-based coupling agent, and isocyanate silane are preferred, and epoxy silane is more preferred.

[0119] When a silane-based adhesion promoter is used, the amount of the silane-based adhesion promoter is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of component (A) and component (B); and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less.

[0120] (Polyisocyanate compounds (diisocyanate compounds)) The primer composition according to the present invention may further contain a diisocyanate compound as a polyisocyanate compound. The diisocyanate compound is not particularly limited as long as it has two isocyanate groups in the molecule. Specific examples of the diisocyanate compound include the diisocyanate compounds listed in the description of component (A-1).

[0121] (pigment) The pigment may be either or both of an inorganic pigment and an organic pigment, such as titanium dioxide, zinc oxide, ultramarine, red iron oxide, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, or sulfate, or an organic pigment such as an azo pigment or copper phthalocyanine pigment.

[0122] (dye) As the dye, any known dye can be used, for example, a black dye, a yellow dye, a red dye, a blue dye, a brown dye, etc.

[0123] (anti-aging agent) Examples of the antioxidant include hindered phenol compounds, hindered amine compounds, and benzotriazole compounds.

[0124] (antistatic agent) Examples of the antistatic agent include hydrophilic compounds such as quaternary ammonium salts, polyglycols, and ethylene oxide derivatives.

[0125] (Flame retardant) Examples of flame retardants include chloroalkyl phosphate, dimethyl methyl phosphonate, bromine-phosphorus compounds, ammonium polyphosphate, neopentyl bromide polyether, and brominated polyether.

[0126] <Method for preparing primer composition> The method for preparing the primer composition of the present invention is not particularly limited, but it can be prepared, for example, using a mixer capable of uniformly mixing liquids. For example, the primer composition can be prepared by weighing out predetermined amounts of the materials constituting the primer composition (component (A), component (B), component (C), component (D), and / or other additives) and mixing the weighed materials using a mixer with a single or double shaft, or a tank with a pulsator or the like at the bottom. In particular, it is preferable to use a device equipped with a jacket that can variably adjust the material temperature.

[0127] <Method of applying primer composition> Although there is no particular limitation on the method for applying the primer composition of the present invention to an adherend, the following application method is preferred as an example: First, the primer composition of the present invention is applied to an adherend by lifting it up, for example, using a brush or paintbrush, so as not to let the liquid drip off, and then applying 50 to 400 ml / m 2 Apply the sealant evenly to the adherend surface in the amount shown. After application, wait 30 minutes to 8 hours before applying the sealant. It is recommended to avoid application in rainy weather or in an environment where water droplets may remain on the adherend surface, and it is recommended to apply the sealant at temperatures between 5°C and 35°C.

[0128] <Application> The primer composition according to the present invention can be suitably used as a primer composition for construction, civil engineering, concrete, wood, metal, glass, plastic, etc., as a sealant, adhesive, etc. Furthermore, the primer composition according to the present invention has excellent jointability with cured sealants, and therefore can be suitably used particularly for sealants.

[0129] The primer composition according to the present invention can also be suitably used as a primer for poorly adhesive coated members. Examples of poorly adhesive coated members for which the primer composition according to the present invention can be used include acrylic electrodeposition coated members, fluorine baked coated members, and anodized coated members. The primer composition according to the present invention can also be used for members other than poorly adhesive coated members.

[0130] <Effects of the embodiment> The primer composition according to the present invention has high barrier properties, and therefore can inhibit the migration of plasticizers and the like from the adherend or sealant, and can exhibit high adhesive durability over a long period of time. The primer composition according to the present invention can also exhibit high adhesion to wet surfaces. Furthermore, the primer composition according to the present invention is also useful as a primer for joining pre-applied sealants. [Example]

[0131] The present invention will be explained in more detail below with reference to examples. It should be noted that these examples are merely illustrative and should not be construed as limiting.

[0132] (Synthesis Example 1: Alkoxysilyl Group-Containing Methacrylic Resin) As an alkoxysilyl group-containing methacrylic resin, a (meth)acrylic polymer having a trimethoxysilyl group was synthesized. Specifically, using 70.00 g of methyl methacrylate, 30.00 g of 2-ethylhexyl methacrylate, 12.00 g of 3-methacryloxypropyltrimethoxysilane, 0.10 g of titanocene dichloride as a metal catalyst, 8.60 g of 3-mercaptopropyltrimethoxysilane, and 20.00 g of benzoquinone solution (95% THF solution) as a polymerization terminator, a (meth)acrylic polymer having a trimethoxysilyl group was obtained according to the method of Synthesis Example 4 of WO2015-088021.

[0133] The ethyl acetate solution of the reaction product obtained was heated at 105°C to determine the solid content, which was 70.5%. The polystyrene-equivalent molecular weight of the obtained polymer measured by gel permeation chromatography (GPC) was 4,000 in weight average molecular weight (Mw) and 2.4 in molecular weight distribution (Mw / Mn). 1 H-NMR measurement (measured using a Shimadzu NMR400 in CDCl3 solvent) confirmed that the compound contained two trimethoxysilyl groups per molecule, and the glass transition temperature was 61°C.

[0134] (Examples and Comparative Examples) For each of Examples 1 to 8 and Comparative Examples 1 to 8, component (A), component (B), component (C), and other additives were mixed and stirred in the proportions shown in Table 1. This resulted in primer compositions according to the Examples and Comparative Examples. The primer compositions obtained in Examples 1 to 8 and Comparative Examples 1 to 8 were then evaluated as follows. The results are shown in Table 1. In Table 1, the amount of each compounded substance is expressed in grams.

[0135] [Table 1]

[0136] Details of the materials shown in Table 1 are as follows: The blending amount of component (B) in Table 1 includes the amount of the solvent. (Component (A)) Desmodur HL (solid content 60%): Mixed isocyanurate trimer of HDI and TDI (TDI:HDI = 3:2) (manufactured by Sumika Covestro Urethane Co., Ltd., isocyanate group concentration 10.5%, solid content 60% by mass, butyl acetate solution) Takenate D-120N (solid content 75%): Adduct of bis(isocyanatomethyl)cyclohexane (hydrogenated XDI) and trimethylolpropane (TMP) (Mitsui Chemicals, solid content 75% by weight, butyl acetate 25% by weight, isocyanate group content in solution 11.0%) Nipporan 3024: Polyester polyurethane resin (manufactured by Tosoh Corporation, solid content 34% by mass, ethyl acetate solution, number average molecular weight: 38,000, weight average molecular weight: 130,000, softening temperature 45°C, Tg: -36°C) EHPE3150: Alicyclic epoxy resin (manufactured by Daicel Corporation, 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol) Pergut S170: Chlorinated polyisoprene (manufactured by Sumika Covestro Urethane Co., Ltd., molecular weight 220,000, chlorine content 64.5% or more)

[0137] (Component (C)) Ketimine coupling agent: N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, weight average molecular weight: 261

[0138] (catalyst) U-360: Nitto Kasei Co., Ltd., mercapto catalyst, dibutyltin isooctylthioglycolate

[0139] (Evaluation method: joint adhesion) The joint adhesion was evaluated as follows. First, a sample of a modified silicone sealant (Cemedine's "POS Seal LM") was prepared as a pre-applied adherend by curing it for 7 days at 23°C and 50% RH. Next, the primer composition according to Example 1 was applied to the surface of the cured sealant (adherend). After leaving it for 30 minutes at 23°C and 50% RH, a bead of a joint-applied modified silicone sealant (Cemedine's "POS Seal LM Ultra Weatherproof") was applied on top to prepare a test specimen. This test specimen was cured for 3 days at 23°C and 50% RH, and then cured for 4 days at 50°C and 40% RH. After that, a portion of the adhesive interface (i.e., a portion of the adhesive interface between the adherend and the modified silicone sealant) was cut with a knife, and the cut portion was peeled off by hand. The peeling state was then visually observed to evaluate the state of failure. The evaluation results are shown in the "Joint Adhesion: POS Seal LM" column in Table 1. The evaluation criteria are as follows:

[0140] "○": The pre-applied and / or post-applied sealant has undergone cohesive failure. "X": Interfacial destruction occurred between the pre-applied sealant and the cured primer composition.

[0141] Furthermore, joint adhesion was evaluated in the same manner as above, except that a sample of modified silicone sealant (Cemedine's "POS Seal LM Ultra Weather Resistant") cured for 7 days in an environment of 23°C and 50% RH was prepared as the pre-applied adherend. The evaluation results are shown in the "Joint Adhesion: POS Seal LM Ultra Weather Resistant" column in Table 1. Furthermore, the other examples and comparative examples were evaluated in the same manner. The evaluation results are shown in Table 1.

[0142] (Evaluation method: Barrier properties) The barrier properties were evaluated as follows: First, a repair paint (manufactured by KMEW) was applied to a slate board according to the coating specifications and allowed to dry for one day. Then, 20 mg / cm of the primer composition according to Example 1 was applied to the slate board. 2 After applying it to the coating film in an amount of 10 mg / cm and drying it for 1 hour, diisononyl phthalate (DINP) was applied on top of it. 2All steps were carried out in an environment of 23°C and 50% RH.

[0143] The resulting test specimen was then left in a 60°C environment for one day, after which the surface of the primer composition coated with DINP was scratched with a metal spatula to evaluate the softening of the paint. The evaluation criteria were as follows. The other examples and comparative examples were also evaluated in the same way. The evaluation results are shown in Table 1.

[0144] "○": No change "△": Some changes are observed "×": Changes are observed

[0145] As can be seen from Table 1, all of the primer compositions according to the examples were shown to have excellent joint adhesion and barrier properties. From the examples and comparative examples, it can be seen that the combination of component (A) and component (B) simultaneously exhibits both good joint adhesion and barrier properties.

[0146] Although the embodiments and examples of the present invention have been described above, the above-described embodiments and examples do not limit the scope of the invention as claimed. It should be noted that not all of the combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention, and that various modifications are possible without departing from the technical concept of the present invention.

Claims

1. A primer composition for adhesion of a sealant, comprising: Component (A) consisting of at least one member selected from the group consisting of a polyisocyanate compound having three or more isocyanate groups, a polyester polyurethane, an epoxy compound, and a chlorinated polymer; Component (B) is an alkoxysilyl group-containing methyl methacrylate polymer having a weight average molecular weight of less than 15,000 and containing 20% ​​by mass or more and less than 80% by mass of methyl methacrylate in the polymer; Contains the amount of component (A) added to the primer composition is 6.0 to 20% in terms of solid content, The primer composition has an added amount of component (B) of 24.9 to 60% in terms of solid content.

2. 2. The primer composition according to claim 1, wherein (B) is an alkoxysilyl group-containing methyl methacrylate polymer containing an alkyl (meth)acrylate ester having an ester group having 8 or more carbon atoms.

3. (C) Amino group-containing silane The primer composition according to claim 1 or 2, further comprising:

4. (D) Silane-based crosslinking agent The primer composition according to any one of claims 1 to 3, further comprising:

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