JPH0978028A - Solventless primer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solventless primer composition sufficiently short in time for developing a first hardness and excellent in workability though the composition is solventless. SOLUTION: This solventless primer composition comprises 40-80wt.% first urethane prepolymer (a) comprising an alkylene glycol having 2-6 carbon atoms and a liquid modified diphenylmethane diisocyanate (c-MDI) and 60-20wt.% second urethane prepolymer (b) comprising a polyester polyol having 200-800 molecular weight and/or a polyether polyol having 76-400 molecular weight and a liquid modified diphenylmethane diisocyanate (c-MDI) as a mixture.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a low melt viscosity,
And, a solvent-free primer composition showing good adhesion to a difficult-to-adhere coated plate and exhibiting an initial hardness quickly, more specifically, a solvent-free window sealant agent for bonding an automobile window glass to a body (painted surface). Prepolymer (a) consisting of alkylene glycol, which adheres well to both the painted surface and exhibits a rapid initial hardness, and polyether glycol /
The present invention relates to a solventless primer composition containing a prepolymer (b) composed of polyester glycol.

[0002]

2. Description of the Related Art Generally, a window sealant is used for bonding a vehicle body and a window glass. However, because of its insufficient adhesion, the glass primer is pre-applied to the window glass and the window sealant side, while the window sealant and the adherend are conventionally applied to the body and window sealant sides. Approximately 70% organic solvent is used to improve the adhesion to the car body.
%, A coating surface primer comprising a urethane prepolymer having a viscosity of several thousand to several tens of thousands cps, a thermoplastic resin, and a tackifier is used.

However, recently, from the viewpoint of environmental protection, the development of a primer that does not use a solvent has been demanded. At the same time, the car body is coated with a hard-to-adhere adhesive such as acrylic melamine resin. Therefore, it shows good adhesion to both the difficult-to-adhere adherend and the window sealant, and the initial hardness when applied to the difficult-to-adhere adherend,
That is, it has a hardness that can be applied with a window sealant as a primer in a short time after application, it can be applied as a thin film of about 10 μm to an adherend having poor adhesiveness, and it cannot be repelled, and it has storage stability. Is desired as a primer for coating a window sealant.

On the other hand, as an adhesive using a urethane prepolymer, for example, in JP-A-6-122860, hydrogenated polybutadiene diol having a molecular weight of 2000 and MDI are used for producing laminated products such as cardboard and plywood. A reactive hot melt adhesive composition obtained by adding a thermoplastic resin and an adhesion promoter to a urethane prepolymer having a viscosity of 300,000 cps or more is disclosed in JP-A-5-214.
311 describes that a urethane prepolymer using a mixed polyol of a polyester polyol and a polyether diol has good storage stability and a high moisture curing rate, and is disclosed in JP-A-2-182774 and JP-A-2-182774. No. 4-164987, a first prepolymer having a glass transition temperature higher than room temperature and a molecular weight of 1,000 or less,
It describes a polyurethane prepolymer consisting of a second prepolymer having a glass transition point of −5 to 10 ° C. and a molecular weight of 1000 or more.

In JP-A-5-117363, a bis (2,2'-diisocyanatephenyl) methane / bis (4,4'-diisocyanatephenyl) methane mixture is reacted with a diol to give 2-isocyanatephenyl-1- It describes a room temperature solid polyurethane resin composition containing a linear polyurethane resin having a methyl group at the terminal. However, these compositions are inadequate as a primer because of poor initial adhesiveness and uneven application when applied thinly, and film formation and adhesiveness to poorly adherent coated plates are still unsatisfactory. It is enough.

Therefore, the present inventors have filed Japanese Patent Application No. 7-905.
No. 06 describes a composition containing only one urethane prepolymer consisting of c-MDI and a polyol such as a low molecular weight polyether polyol. Although this composition is excellent in adhesiveness to a difficult-to-adhesive coating surface and film-forming property, it cannot be said that the time required from applying the primer to the coated plate to loading the sealant thereon is sufficiently short, There were cases where workability was not very good.

Separately from this, an adhesive containing a polyisocyanate is described in JP-B-48-4932, which is used to prevent discoloration of the adhesive.
Since tetraisocyanate is used, there is no description about the adhesiveness to a difficult-to-adhere coated plate.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the primer composition, and to obtain an adherend which has a low melt viscosity at low temperature (60 to 80 ° C.) while being solvent-free. It can be applied thinly, and the initial hardness development time is sufficiently short. Therefore, the time from the application of the primer to the hardening of the sealant to prevent the sealant from shifting does not occur. It is to provide a solvent-free primer composition as a primer that sufficiently adheres to a sealant. The present invention achieves at least one of the above objects.

[0009]

The present inventors have found that the number of carbon atoms is 2
~ 6 alkylene glycol and c-MDI urethane prepolymer, polyester polyol and /
Alternatively, a primer composition prepared by separately preparing two types of prepolymers of a polyether polyol and a urethane prepolymer composed of c-MDI and then mixing them may be applied to a coated surface, and then the primer may carry a window sealant. It was found that the time for developing the possible initial hardness was sufficiently short, and the present invention was achieved.

That is, the present invention relates to a first urethane prepolymer (a) consisting of an alkylene glycol having 2 to 6 carbon atoms and a liquid modified product of diphenylmethane diisocyanate (c-MDI), a polyester polyol having a molecular weight of 200 to 800, and Or a mixture of a polyether polyol having a molecular weight of 76 to 400 and a second urethane prepolymer (b) composed of a liquid modified product of diphenylmethane diisocyanate (c-MDI), and the first urethane prepolymer (a). A solventless primer composition in which the second urethane prepolymer (b) is present in a weight ratio of 40:60 to 80:20.

The alkylene glycol having 2 to 6 carbon atoms in the first urethane prepolymer (a) is
It is preferably 4-butanediol.

Further, the first urethane prepolymer (a)
Are preferably prepolymers produced with an NCO / OH ratio of 5.0 to 8.0. Further, the second urethane prepolymer (b) is preferably a prepolymer produced with an NCO / OH ratio of 4.0 to 8.0.

Then, 0.02 to 0.8 parts by weight of the moisture curing catalyst and / or 100 parts by weight of the total amount of the first urethane prepolymer (a) and the second urethane prepolymer (b) are used. Alternatively, it preferably contains 0.5 to 10 parts by weight of the latent curing agent.

The present invention will be described in detail below. The solventless primer composition of the present invention comprises a first urethane prepolymer (a) composed of an alkylene glycol having 2 to 6 carbon atoms and a liquid modified product of diphenylmethane diisocyanate (c-MDI), and a polyester having a molecular weight of 200 to 800. It is characterized by mixing a polyol and / or a polyether polyol having a molecular weight of 76 to 400 with a second urethane prepolymer (b) made of a liquid modified product of diphenylmethane diisocyanate (c-MDI).

The first urethane prepolymer (a) is obtained by reacting an alkylene glycol having 2 to 6 carbon atoms with a liquid modified product of diphenylmethane diisocyanate (c-MDI). The alkylene glycol having 2 to 6 carbon atoms is a compound having 2 to 6 carbon atoms and obtained by substituting two hydroxyl groups for two hydrogen atoms on a carbon atom of a hydrocarbon containing only carbon in the skeleton. The alkylene group, which is a hydrocarbon group in the chain, may be linear or branched. Since alkylene glycol is used, it has excellent initial hardness expression and adhesiveness.

Specifically, ethylene glycol, 1,4
-Butanediol, heptanediol, hexanediol, neopentyl glycol, etc.
4-Butanediol is preferable in terms of melt viscosity and adhesiveness. These polyols used for the first urethane prepolymer (a) may be used alone or in a mixture thereof.

The isocyanate used in the present invention is a liquid modified product of diphenylmethane diisocyanate (hereinafter referred to as c-M).
DI) or carbodiimide-modified diphenylmethane diisocyanate (hereinafter referred to as carbodiimide-modified MDI
, Or a mixture thereof. c-MDI
Is a polymer obtained by polymerizing a monomer of pure MDI (hereinafter referred to as pure-MDI), and can be obtained by phosgenation of diamino-diphenylmethane, which is a condensate of aniline and formalin, for example. Furthermore, pure MD
Also included are modified MDIs liquefied by reacting I with low molecular weight glycols such as ethylene glycol, propylene glycol, etc., or long chain polyols.

As the c-MDI, a polymeric MD is used.
I, 4,4'-MDI, 2,4'-MDI and 2,
Examples include MDI isomers including 2'-MDI, or a mixture thereof. Here, pure-MDI means 4,4'-
It means a monomer of one of MDI, 2,4'-MDI or 2,2'-MDI. These are preferable because the reaction can be easily controlled. Specifically, a commercially available product such as 44V10 manufactured by Sumitomo Bayer Urethane Co., Ltd. can be used.

The average number of functional groups per molecule of c-MDI is preferably 2.1 to 3.1, more preferably 2.6 to 2.9. When it is less than 2.1, the film forming property and the adhesive property are poor, and
If it exceeds 1, the melt viscosity tends to be high. The c-MDI used in the present invention is a mixture of these MDI isomers, or a polymeric MDI and one or more kinds of pure-M.
It may be a mixture with DI.

A carbodiimide-modified MDI can be used in place of the c-MDI. This carbodiimide-modified MDI is one in which two MDIs are bonded via a carbodiimide group, and for example, pure-MDI is , A modified MDI or the like obtained by heating and reacting in the presence of a catalyst such as a phosphorus-based compound such as 1-ethyl-3-methyl-3-phosphorin-1-oxide, and dimerizing a part thereof to form carbodiimid Be done. Specifically, a commercially available product such as Coronate MTL manufactured by Nippon Polyurethane Co., Ltd. can be used.

The first urethane prepolymer (a) is obtained by reacting a polyol with an excess of a compound having an isocyanate group at the molecular end. When the first urethane prepolymer (a) is produced, the reaction between the alkylene polyol having 2 to 6 carbon atoms and c-MDI is the same as NC in c-MDI.
Ratio of O groups to OH in alkylene polyol (NCO /
It is necessary to add an excess amount of c-MDI so that the (OH ratio) becomes 5.0 to 8.0, particularly 5.0 to 7.0, and react the resulting mixture in terms of workability, curability, and adhesiveness. preferable.

The second urethane prepolymer (b) is a polyester polyol having a molecular weight of 200 to 800 and / or
Alternatively, it can be obtained by reacting a polyether polyol having a molecular weight of 76 to 400 with c-MDI. As the isocyanate compound used for the second urethane prepolymer (b), the same c-MDI as used for the above-mentioned first urethane prepolymer (a) is used.

The polyether polyol is a compound having a skeleton obtained by addition-polymerizing one or more alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide with a compound having two or more active hydrogens. is there. Alternatively, it is a compound having two hydroxyl groups at the molecular end by ring-opening polymerization of tetrahydrofuran or the like.

Examples of the compound having two or more active hydrogens include polyhydric alcohols, amines, alkanolamines and polyhydric phenols. As the polyhydric alcohols, ethylene glycol, propylene glycol, butanediol, diethylene glycol, glycerin, hexanetriol, trimethylolpropane, pentaerythritol, etc., and the amines, ethylenediamine, hexamethylenediamine, etc.,
Propanolamine and the like, and polyhydric phenols include resorcin, bisphenol A and the like.

Specifically, polytetramethylene ether glycol (PTMG), polyoxypropylene glycol (PPG), polyethylene glycol (PEG),
And the like, and particularly PPG, PTMG and the like are preferable.
Further, it may be a mixture of two or more kinds.

Polyester polyols include ethylene glycol, propylene glycol, butanediol, diethylene glycol, glycerin, hexanetriol,
Trimethylolpropane, diols such as pentaerythritol and caprolactate polyester polyols obtained by ring-opening polymerization of triol and ε-caprolactone and the like; maleic acid, fumaric acid, phthalic acid, adipic acid, sebacic acid, phthal, maleic acid, citric acid,
Condensed polyester polyols obtained by dehydration condensation reaction of polybasic acids such as trimellitic acid with diols or triols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, glycerin, hexanetriol, trimethylolpropane, pentaerythritol, etc. Is mentioned. Specific examples thereof include polycaprolactone polyol (PCL), ethylene adipate, diethylene adipate, butylene adipate, and the like, and a mixture of two or more kinds may be used. The polyol used for the second urethane prepolymer (b) may be a mixture of the above polyether polyol and polyester polyol.

The molecular weight of the polyol used for the second urethane prepolymer (b) is preferably 200 to 800, particularly 300 to 500 in the case of polyester polyol, and 76 to 40 in the case of polyether polyol.
It is preferably 0, particularly 76 to 250. When the molecular weight of the polyol is lower than the above range, the urethane prepolymer obtained has a high NCO content, so that the storage stability is poor, and when the molecular weight of the polyol is higher than the above range, the adhesion to the poorly-adhesive coated plate is poor.

30 to 6 of the above-mentioned c-MDI and polyether polyol and / or polyester polyol.
The urethane prepolymer (b) is obtained by reacting at 0 ° C. in a nitrogen atmosphere under normal pressure. When producing the second urethane prepolymer (b), the NCO / OH ratio of the reaction between the polyol and the isocyanate group-containing compound is 4.0 to 8.
It is preferably in the range of 0, particularly 4.0 to 7.0.
If it is less than 4.0, the viscosity increases and the workability is poor, and if it exceeds 8.0, the film forming property and the curability deteriorate.

First urethane prepolymer (a): second
The mixing ratio of the urethane prepolymer (b) in
40:60 to 80:20, especially 50:50 to 70:30
It is preferred that When the mixing ratio of the first urethane prepolymer (a) is lower than this range, the initial hardness is delayed and workability is poor, and when the mixing ratio of (a) is too high, the viscosity is increased by heating for a long time. However, workability deteriorates.

Further, the solventless primer composition of the present invention preferably contains a moisture curing catalyst and / or a latent curing agent. The moisture curing catalyst or latent curing agent may be contained alone, or both the moisture curing catalyst and latent curing agent may be contained. Moisture curing catalysts that can be used in the present invention include dioctyltin laurate (DOTL), dibutyltin dilaurate, dibutyltin diacetate,
Examples thereof include tin-based catalysts such as dibutyltin-markerbutide and dioctyltin-dimerbutide, and nitrogen-containing compounds such as triethylamine, triethylenediamine, tetramethylguanidine and morpholine.

In the case of a tin-based catalyst, the content of the moisture-curing catalyst is 0.02 to 0.8 parts by weight, and particularly 0 to 0.8 parts by weight based on 100 parts by weight of the total amount of the urethane prepolymers (a) and (b). It is preferably 0.02 to 0.4 in terms of storage stability, curability and adhesiveness. In the case of a nitrogen-containing compound, 0.05 to 0.8 parts by weight, particularly 0.1 to 0. 0 parts by weight based on 100 parts by weight of the total amount of urethane prepolymers (a) and (b).
It is preferably 7 parts by weight from the viewpoint of storage stability, curability and adhesiveness.

Examples of the latent curing agent used in the present invention include N-hydroxyethyl-2-isopentyloxazolidine, its XDI adduct, and other oxazolidines. The content of the latent curing agent is 0.5 to 10 parts by weight, particularly 0.5 to 8 parts by weight, based on 100 parts by weight of the total amount of the urethane prepolymers (a) and (b). It is preferable in terms of curability and adhesiveness.

Further, the solventless primer composition of the present invention may contain, in addition to the urethane prepolymer, if necessary.
Additives such as fillers, catalysts, stabilizers, tackifiers, plasticizers, colorants, heat stabilizers, and ultraviolet absorbers may be added within the range not impairing the gist of the present invention.

Examples of the filler include calcium carbonate, barium sulfate, talc, clay, titanium oxide, carbon black, white carbon and the like. Examples of the tackifier include rosin or its derivative, natural resin such as terpene resin, petroleum resin, hydrogenated petroleum resin and the like. Examples of the plasticizer include phthalic acid ester, aliphatic dibasic acid ester, glycol ester and the like.
Examples of the colorant include titanium oxide and carbon.

In the solventless primer composition of the present invention, the first urethane prepolymer (a) and the second urethane prepolymer (b) are produced separately, and then the (a) and (b) are prepared. Further, if necessary, other additives may be appropriately added and mixed at a temperature of 70 to 90 [deg.] C. for 1 to 2 hours while being mixed to produce.

The NCO content of the solvent-free primer composition of the present invention thus produced is 17.0-2.
It is 6.5%, especially 20.0 to 26.0%. The viscosity is
The viscosity at 80 ° C is preferably 100 to 1000 cps. When the viscosity exceeds 1000 cps, the viscosity in the application temperature range (about 60 to 90 ° C.) is too high, and it is difficult to apply thinly on the adherend. Furthermore, since the solventless primer composition of the present invention has a small viscosity change during heating coating and storage in a container, it does not thicken in storage for about 6 to 12 months and has storage stability, which is difficult. Good film-forming property and adhesive property to an adhesive coated plate, and early development of initial hardness, and adhesive property develops in about 3 days after application of window sealant.

The solventless primer composition thus obtained is useful as a primer for a window sealant and a non-adhesive coated plate. The method for adhering the window sealant and the hardly-adhesive coated plate using the solventless primer composition of the present invention will be described below. One of the adherends used in the present invention is a coated steel plate used for an automobile body or the like, for example,
An example of such a hard-to-adhesive coated plate is an electrodeposition-coated steel plate or the like, which is baked with acrylic melamine paint.

The window sealant used in the present invention is
It is for bonding the car body and window glass,
Commonly used polyurethane sealants and the like can be mentioned. As the window sealant, for example, a commercially available product such as WS-70 manufactured by Yokohama Rubber Co., Ltd. can be used.

One example of the method of applying the solventless primer composition of the present invention as a primer is 60 to 80 when the above-mentioned adherend having poor adhesiveness and the window glass are adhered via a window sealant. After applying the composition of the present invention as a primer to the above-mentioned difficult-to-adhere substrate by using, for example, a commercially available applicator at 0 ° C., it is cooled and solidified to obtain a window sealant coating primer having sufficient initial adhesive strength. A film is formed. After the window sealant coating primer is formed, a window sealant is applied on the primer, and the window glass and the window sealant are brought into close contact with each other and adhered to each other so that the automobile body and the window glass are adhered to each other to produce a molded article. .

Further, when adhering the window sealant and the window glass, a primer for the window glass may be applied to one or both of the contact surfaces of the window glass and the window sealant, if necessary. As the primer for this window glass, a generally used urethane-based or silane-based primer can be used.

The solvent-free primer composition of the present invention, as a primer for coating a window sealant, exhibits sufficient initial adhesiveness to an adherend having poor adhesion. Further, the curing is completed 1-2 days after the application. After curing, it exhibits sufficient water resistance.

[0042]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by the examples. (Examples 1 to 6 and Comparative Examples 1 to 3) 1. Production of urethane prepolymer 1,4-butanediol having a number average molecular weight of 90 was placed in a reaction vessel, dehydrated under reduced pressure at 110 ° C. and 50 mmHg for 2 hours, and then cooled to 50 ° C., to which a liquid modified diphenylmethane diisocyanate [Sumitomo 4 made by Bayer Urethane
4V10 (average functional group number: 2.6 to 2.7)] is added and reacted at 60 ° C. for 10 hours with stirring at an NCO / OH ratio shown in Table 1 below to give a urethane prepolymer (a). Manufactured. Separately, a polyester polyol or polyether polyol having each number average molecular weight shown in Table 1 below was placed in a reaction vessel, and the temperature was 110 ° C. and 50 mm.
After dehydration under reduced pressure with Hg for 2 hours, the mixture was cooled to 50 ° C., and diphenylmethane diisocyanate liquid modified product [44V10 (Sumitomo Bayer Urethane Co., Ltd., average number of functional groups: 2.6 to 2.7)] was added to 60. A urethane prepolymer (b) was produced by reacting at an NCO / OH ratio shown in Table 1 below at 10 ° C. with stirring.

Regarding Examples 2 to 6 and Comparative Examples 1 to 3,
In the same manner as in Example 1, the polyols shown in Table 1 below were reacted at the ratios shown in Table 1 below to produce urethane prepolymers. In Example 5, a catalyst was further added and the reaction was carried out in the same manner as in Example 1. In Example 6, a latent curing agent was further added and the reaction was carried out in the same manner as in Example 1. The NCO content of the obtained urethane prepolymer is shown in Table 1 below.

2. Production of solvent-free primer composition 1. 100 parts by weight of the urethane prepolymer mixture obtained by thoroughly mixing the urethane prepolymers (a) and (b) obtained in 1. at the compounding ratio shown in Table 1 below was added as an additive to Polyflow No. manufactured by Kyoei Chemical Co., Ltd. 0.8 parts by weight of 90 was added and stirred at 50 ° C. to obtain each solvent-free primer composition. The obtained composition was applied to an adherend (electrodeposition coated plate on which acrylic melamine was baked) at a melting temperature of 80 ° C., and the film-forming property when applied was evaluated. The viscosity of the obtained composition is shown in Table 1 below. Example 5 is a solventless primer composition in the same manner as in Examples 1 to 4, except that the catalysts shown in Table 1 below were added when the urethane prepolymers (a) and (b) were mixed. Got Example 6 is a solvent-free type similar to Examples 1 to 4, except that the latent curing agent shown in Table 1 below was added when the urethane prepolymers (a) and (b) were mixed. A primer composition was obtained. Further, after the primer was cooled and solidified, a window sealant (WS-70 manufactured by Yokohama Rubber Co., Ltd.) was applied in a thickness of 3 mm as an adhesive, and an adhesion test was conducted under the following conditions.

To test the initial adhesion, 20 ° C.,
After standing at 65% RH for 7 days, a hand peel test was conducted while cutting the adhesive surface with a knife. In order to test the anti-window washer liquid, the film was left at 20 ° C. and 65% RH for 3 days, and then left in a 50% strength window washer liquid for 10 days, and then a hand peel test was performed while cutting the adhesive surface with a knife. The results are shown in Table 1 below.

(Physical Properties Test) Substrate: Electrodeposited plate baked with acrylic melamine 1. Film Formability The uniformity of the coating film on the adherend was evaluated according to the following criteria. Evaluation criteria: ◯: A uniform coating film was produced. △: Some coating unevenness was observed.

2. Adhesiveness The adhesiveness of the solventless primer composition of the present invention to the adherend (electrodeposited acrylic melamine coated plate and window sealant) was evaluated according to the following criteria. Evaluation criteria: ◎ …… Window sealant breaks 95% or more of the bonded area ○ …… Window sealant breaks 8 of the bonded area
0% or more × …… The breakage of the window sealant is 8 in the bonded area.
Less than 0% 3. Viscosity The viscosity at 80 ° C was measured by an E-type viscometer manufactured by Toki Sangyo Co., Ltd. 4. Initial hardness development time From the time when each primer composition was applied to the electrodeposited acrylic melamine coated plate, until the primer solidifies to a hardness that allows the window sealant to be applied (to such an extent that the window is not dropped by standing the coated plate vertically). The time (minutes) required for the measurement was measured.

[0048]

[Table 1] Note) PPG: tripropylene glycol BD: 1,4-butanediol PCL: polycaprolactone Catalyst: dibutyltin dilaurate (DOTL) Latent curing agent: N-hydroxyethyl-2-isopentyloxazolidine

[0049]

The solventless primer composition of the present invention comprises
Despite being solvent-free, it has a low viscosity at the temperature of construction and can be applied thinly. Furthermore, the viscosity change is small during heating coating and storage in a container. The film-forming property and the adhesive property to the difficult-to-adhere coating plate are good, and the initial hardness development time is sufficiently short in spite of being solvent-free, so that the adhesion between the difficult-to-adhere coating plate and the window sealant of an automobile, etc. When
The sealant can be applied immediately after applying the primer, and it has excellent workability. Therefore, it is useful as a solvent-free primer for difficult-to-adhere coated plates. Further, for example, the composition of the present invention is solvent-free, and thus is excellent in environmental protection, as compared with a primer used for bonding a window sealant to an ordinary automobile body using an organic solvent of about 70%. The present invention has at least one of these effects.

Claims (5)

[Claims] 1. A liquid modified product (c-M) of an alkylene glycol having 2 to 6 carbon atoms and diphenylmethane diisocyanate.
A first urethane prepolymer (a) composed of DI),
Liquid modified product of polyester polyol having a molecular weight of 200 to 800 and / or polyether polyol having a molecular weight of 76 to 400 and diphenylmethane diisocyanate (c
-MDI) second urethane prepolymer (b)
And the first urethane prepolymer (a) and the second urethane prepolymer (b) are present in a weight ratio of 40:60 to 80:20. Solventless primer composition. 2. The solventless primer composition according to claim 1, wherein the alkylene glycol having 2 to 6 carbon atoms in the first urethane prepolymer (a) is 1,4-butanediol. 3. The first urethane prepolymer (a)
Is a prepolymer produced at an NCO / OH ratio of 5.0 to 8.0, and the solventless primer composition according to claim 1 or 2. 4. The second urethane prepolymer (b)
Is a prepolymer produced with an NCO / OH ratio of 4.0 to 8.0. The solventless primer composition according to claim 1. 5. A total amount of 10 of the first urethane prepolymer (a) and the second urethane prepolymer (b).
Solvent-free according to any one of claims 1 to 4, containing 0.02 to 0.8 part by weight of a moisture curing catalyst and / or 0.5 to 10 parts by weight of a latent curing agent, relative to 0 part by weight. Mold primer composition.