JPH07103357B2 - Adhesive composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive composition, and more specifically, a polyester-based adhesive used for laminating a vinyl chloride film and a metal plate and the like. The present invention relates to improvement of the adhesive performance of the composition.

[Outline of Invention]

The present invention enables low-temperature adhesion by mixing hydrophobic silica into a polyester adhesive mainly composed of a polyester resin having a glass transition temperature T _G of 50 to 80 ° C, has high peel strength, and is water resistant. The present invention aims to provide an adhesive composition having excellent adhesion reliability.

[Conventional technology]

Generally, a vinyl chloride film and a metal plate such as an iron plate and a zinc plate are bonded together by using an adhesive.

Conventionally, acrylic adhesives, polyester adhesives, and the like have been mainly known as the adhesives.

However, since the acrylic adhesive is mainly composed of a methyl methacrylate polymer having a high glass transition temperature, it is necessary to perform high temperature lamination in order to bond the vinyl chloride film to the metal plate. Since the vinyl chloride film is not so high in heat resistance, for example, when the vinyl chloride film surface is embossed and various patterns are formed on it and laminated at a high temperature, the pattern disappears or vinyl chloride film The smoothness of the film surface becomes high and the appearance is damaged, such as gloss,
There is a problem that the value of a product obtained by processing a vinyl chloride film on a metal plate is reduced.

On the other hand, the polyester adhesive can be laminated and bonded at a relatively low temperature as compared with the acrylic adhesive, and the appearance commercial value is maintained. However, this polyester adhesive generally has low water resistance, and for example, when the peel strength is measured after performing a boiling vinegar penetration test, the result is much lower than the initial value immediately after lamination, and the weather resistance and the reliability are low. Causes problems.

[Problems to be solved by the invention]

As described above, when the vinyl chloride film is adhered to the metal plate, the use of an acrylic adhesive that must be subjected to high temperature lamination causes a problem that the appearance is deteriorated and the commercial value is reduced. In addition, a polyester-based adhesive that can be laminated at a low temperature does not impair the appearance but is inferior in water resistance, which causes a problem in reliability.

Therefore, it is an object of the present invention to provide an adhesive composition having excellent adhesion reliability by making use of low-temperature adhesiveness, which is an advantage of a polyester-based adhesive, to impart water resistance and high peel strength to the adhesive.

[Means for solving problems]

The present inventors have developed a polyester adhesive having water resistance and high peel strength, and as a result of extensive research over a long period of time, the hydrophobic silica is useful for imparting water resistance,
It has been found that by mixing this hydrophobic silica with a polyester adhesive and further adding a polyisocyanate compound, it effectively acts to improve water resistance and peel strength.

The present invention was completed based on such findings, and is an adhesive composition for adhering a vinyl chloride film and a metal plate, having a glass transition temperature T _G of 50 to 80 ° C. of a polyester resin 50 wt. % Or more and 5 to 50% by weight of hydrophobic silica,
The polyisocyanate compound is characterized by comprising 0.1 to 50% by weight.

In the adhesive composition of the present invention, the main polyester resin is synthesized by reacting a polyhydric alcohol and a polybasic acid at a predetermined ratio.

Examples of the polyhydric alcohol used include ethylene glycol, diethylene glycol, propylene glycol, 1,4 butanediol, neopentyl glycol, 1,4 cyclohexanedimethanol and the like.

Examples of polybasic acids include aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid.

The polyester resin synthesized from the polyhydric alcohol and the polybasic acid desirably has a number average molecular weight of about 5,000 to 25,000 and a glass transition temperature T _G of 50 to 80 ° C.

Here, the number average molecular weight is set to about 5000 to 25000 because the predetermined adhesive properties cannot be obtained if the number average molecular weight is out of this range and the glass transition temperature is cross-linked by a cross-linking agent added later as an adhesive composition. This is because there is a possibility that it will be higher than the value.

Further, the glass transition temperature T _{G is set} to 50 to 80 ° C., because if it is less than 50 ° C., it may hinder the handling at room temperature.
This is because the heating temperature at the time of adhesion becomes too high and the appearance of the adhered vinyl chloride film may be impaired.

The glass transition temperature T _G of the polyester resin can be easily controlled by changing the type and blending ratio of the polyhydric alcohol and polybasic acid used. For example, neopentyl glycol 25 mol% ethylene glycol 25 mol% Terephthalic acid 25 mol% Isophthalic acid 25 mol% The composition has a glass transition temperature of 65 ° C, neopentyl glycol 25 mol% ethylene glycol 25 mol% terephthalic acid 10 mol% isophthalic acid 25 mol% adipic acid 15 mol% With such a composition, the glass transition temperature is set to 50 ° C.

Of course, the present invention is not limited to this, and a polyhydric alcohol or a polybasic acid may be selected according to the purpose of use and appropriately set so that the glass transition temperature falls within the above-mentioned temperature range.

On the other hand, the hydrophobic silica is added for the purpose of imparting water resistance to the adhesive mainly composed of polyester resin. This hydrophobic silica has a particle size of about 0.005 to ²⁰ μm and a specific surface area of 50 to 300 m ² / g obtained by a wet method or a dry method.
The surface of such fine silica particles is subjected to a hydrophobic treatment with an organic compound having a silica-reactive group at one end and a lipophilic group at the other end.

The surface treatment of the fine silica particles is performed by chemically reacting and binding the above-mentioned organic compound. Examples of usable organic compounds include organic silicon compounds, for example, silane coupling agents having a hydrophobic organic group.
Specifically, for example, C ₆ H ₅ Si (OC ₂ H ₅ ) ₃ , CH ₃ Si (OC
_{2 H 5) 3, CH 3} Si (OCH 3) is _{3, CH 3 (CH 2)} 7 Si (OC 2 H 5) 3 and the like. Furthermore, dimethyl silicone oil as an organosilicon compound Can be used.

Alternatively, in addition to the above organic silicon compound, a titanium coupling agent or the like can be used. As the titanium coupling agent, any conventionally known one can be used, for example, Etc.

The polyisocyanate compound is a compound having two or more isocyanate groups [-N = C = O] and acts as a crosslinking agent that crosslinks by an addition reaction.

As the polyisocyanate compound, methylphenyldiisocyanate (MDI) -based isocyanate is excellent in heat resistance, and examples thereof include methylene-bis- (4-phenylisocyanate). Still other polyisocyanates include tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate,
Examples thereof include xylylene diisocyanate, naphthylene diisocyanate, lysine isocyanate, dicyclohexylmethane diisocyanate, triphenylmethane triisocyanate, tris (P-isocyanatephenyl) thiophosphate, polymethylene polyphenyl polyisocyanate and the like.

Each of the adhesive compositions described above contains 50% by weight of polyester resin.
As described above, the hydrophobic silica may be mixed in a ratio of 5 to 50% by weight and the polyisocyanate compound in a range of 0.1 to 50% by weight. Regarding the polyester resin, if it is less than 50% by weight, the adhesive effect is deteriorated and it is set to 50% by weight or more because of the relationship with other additive compositions. 5% by weight of hydrophobic silica
If it is less than 50% by weight, the hydrophobic effect cannot be expected, and if it exceeds 50% by weight, the effect of adhering the polyester resin to the vinyl chloride film is hindered. The polyisocyanate compound is 0.
If it is less than 1% by weight, the crosslinking effect cannot be expected, and if it exceeds 50% by weight, the adhesive strength after the boiling water resistance test is lowered due to the influence of the unreacted polyisocyanate compound.

The adhesive composition containing the above polyester resin, hydrophobic silica, and polyisocyanate compound as a basic composition further includes an ethyleneimine-based crosslinking agent or a diazabicycloundecene (DBU) -based crosslinking agent that acts as a catalyst for crosslinking. May be added.

Examples of the ethyleneimine-based cross-linking agent include compounds shown below.

Also, as the DBU-based crosslinking agent, 1,8-diaza-bicyclo- (5.4.0) -7-undecene (DBU), DBU-phenol salt, DBU-octylate, DBU-p-toluenesulfonate, DBU-formate, DBU
Examples thereof include oleate.

As other cross-linking agents, tertiary amines and the like can be used because they are considered to have a cross-linking promoting effect.

When the ethyleneimine-based crosslinking agent, DBU-based crosslinking agent is added to the adhesive composition, the addition amount is 0.1 ~ 10
%, Preferably 0.3-1% by weight
Is more preferable. If the addition amount is less than 0.1% by weight, the crosslinking effect cannot be expected, and if it is 10% by weight or more, the glass transition temperature of the polyester resin becomes high and the low temperature adhesion effect is hindered.

The adhesive composition having the above-mentioned composition is usually used by adding a solvent to adjust the viscosity and the like, and any general-purpose solvent can be used in this case. Of these, ketone solvents such as toluene and methyl ethyl ketone are preferable. Further, the compounding ratio of the solvent and the adhesive composition may be appropriately set according to the desired viscosity and the like.

[Action]

In the adhesive composition of the present invention, by adding hydrophobic silica, the hydrophobicity of the adhesive is improved, the adhesiveness is secured even after the boiling water test, and the water resistance is improved.

Further, the glass transition temperature is controlled by changing the combination and ratio of the polyhydric alcohol and the polybasic acid used when synthesizing the polyester resin, and the temperature range is 50 to 80.
By setting the temperature to ℃, low temperature adhesion becomes possible.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

Example 1 First, 25 mol% of neopentyl glycol, 25 mol% of ethylene glycol, 25 mol% of terephthalic acid and 25 mol% of isophthalic acid were reacted to synthesize a polyester resin A having a glass transition temperature of 65 ° C.

Then, an adhesive composition was obtained by mixing the following composition mainly composed of polyester resin A.

Polyester resin A 100 parts by weight Polyisocyanate compound (manufactured by Nippon Polyurethane Company, trade name Millionate MR) 5 parts by weight Hydrophobic silica (manufactured by Nippon Silica Company, trade name Nipseal E)
-200A-Meltriethoxysilane treatment) 25 parts by weight Ethyleneimine-based cross-linking agent (Nippon Shokubai Kagaku Co., trade name TA
Z: ω-aziridinylpropionic acid-2,2-dihydroxylmethyl-butanol ester) 1 part by weight Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight Example 2 First, neopentyl glycol 25 mol%, ethylene glycol 25 mol% , 25 mol% of terephthalic acid and 25 mol% of isophthalic acid were reacted to synthesize polyester resin A having a glass transition temperature of 65 ° C.

On the other hand, neopentyl glycol 50 mol%, dimethyl terephthalate 15 mol%, dimethyl isophthalate 15 mol%
And 20 mol% of succinic anhydride are reacted to cause a glass transition temperature of 5
A polyester resin B at ℃ was synthesized.

Then, the compositions containing polyester resin A and polyester resin B shown below were mixed to obtain an adhesive composition.

Polyester resin A 95 parts by weight Polyester resin B 5 parts by weight Polyisocyanate compound (Nippon Polyurethane Co., trade name Coronate C-2516) 25 parts by weight Hydrophobic silica (Nippon Silica Co., trade name Nipseal SS)
50A) 25 parts by weight Ethyleneimine crosslinking agent (Nippon Shokubai Kagaku Co., trade name TA
Z) 1 part by weight Silane coupling agent (manufactured by Nippon Unicar, trade name Epoxysilane A-187) 1 part by weight Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight Comparative Example 1 This example is an example in which hydrophobic silica is not added. Is.

First, 25 mol% of neopentyl glycol, 25 mol% of ethylene glycol, 25 mol% of terephthalic acid, and 25 mol% of isophthalic acid were reacted to synthesize a polyester resin A having a glass transition temperature of 65 ° C.

Then, an adhesive composition was obtained by mixing the following composition mainly composed of polyester resin A.

Polyester resin A 100 parts by weight Polyisocyanate compound (manufactured by Nippon Polyurethane Company, trade name Millionate MR) 5 parts by weight Ethyleneimine cross-linking agent (manufactured by Nippon Shokubai Chemical Co., trade name TA
Z) 1 part by weight Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight Comparative Example 2 This example is an example using untreated silica whose surface is not hydrophobically treated.

First, 25 mol% of neopentyl glycol, 25 mol% of ethylene glycol, 25 mol% of terephthalic acid, and 25 mol% of isophthalic acid were reacted to synthesize a polyester resin A having a glass transition temperature of 65 ° C.

On the other hand, neopentyl glycol 50 mol%, dimethyl terephthalate 15 mol%, dimethyl isophthalate 15 mol%
And 20 mol% of succinic anhydride are reacted to cause a glass transition temperature of 5
A polyester resin B at ℃ was synthesized.

Then, the compositions containing polyester resin A and polyester resin B shown below were mixed to obtain an adhesive composition.

Polyester resin A 95 parts by weight Polyester resin B 5 parts by weight Polyisocyanate compound (manufactured by Nippon Polyurethane Company, trade name Coronate C-2516) 5 parts by weight Untreated silica (manufactured by Nippon Silica Company, trade name Nipseal E)
-200- No treatment 25 parts by weight Ethyleneimine-based cross-linking agent (Nippon Shokubai Kagaku Co., trade name TA
Z) 1 part by weight Silane coupling agent (manufactured by Nippon Unicar, trade name Epoxysilane A-187) 1 part by weight Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight Comparative Example 3 In this example, the amount of hydrophobic silica added is 50 parts by weight. This is an example of exceeding%.

First, 25 mol% of neopentyl glycol, 25 mol% of ethylene glycol, 25 mol% of terephthalic acid, and 25 mol% of isophthalic acid were reacted to synthesize a polyester resin A having a glass transition temperature of 65 ° C.

Then, an adhesive composition was obtained by mixing the following composition mainly composed of polyester resin A.

Polyester resin A 100 parts by weight Polyisocyanate compound (Nippon Polyurethane Co., trade name Millionate MR) 15 parts by weight Hydrophobic silica (Nippon Silica Co., trade name Nipseal SS)
50A) 120 parts by weight Ethyleneimine-based cross-linking agent (Nippon Shokubai Kagaku Co., trade name TA
Z) 1 part by weight Silane coupling agent (manufactured by Nippon Unicar, trade name Epoxysilane A-187) 1 part by weight Toluene 400 parts by weight Methyl ethyl ketone 400 parts by weight Comparative Example 4 In this example, the polyester resin has a glass transition temperature of 80 ° C. It is an example that goes beyond.

First, neopentyl glycol 15 mol%, hydrogenated bisphenol A 20 mol%, 1,4-cyclohexanedimethanol 1 mol%
Glass transition temperature 85 by reacting 5 mol%, dimethyl terephthalate 25 mol% and dimethyl isophthalate 25 mol%
A polyester resin C at ℃ was synthesized.

Then, an adhesive composition was obtained by mixing the following composition mainly composed of polyester resin C.

Polyester resin C 100 parts by weight Polyisocyanate compound (Nippon Polyurethane Co., Coronate C-2516) 10 parts by weight Hydrophobic silica (Nippon Silica, trade name Nipseal SS)
50A) 25 parts by weight Ethyleneimine crosslinking agent (Nippon Shokubai Kagaku Co., trade name TA
Z) 1 part by weight Silane coupling agent (manufactured by Nippon Unicar, trade name Epoxysilane A-187) 1 part by weight Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight Comparative Example 5 This example shows that the polyester resin has a glass transition temperature of less than 50 ° C. Is an example of.

First, 25 mol% of propylene glycol, 15 mol% of 1,4-cyclohexanedimethanol, 35 mol% of propylene glycol, 15 mol% of dimethyl terephthalate and 25 mol% of dimethyl isophthalate are reacted to give a polyester resin D having a glass transition temperature of 35 ° C. Synthesized.

Then, an adhesive composition was obtained by mixing the following composition mainly composed of polyester resin D.

Polyester resin D 100 parts by weight Polyisocyanate compound (manufactured by Nippon Polyurethane Company, trade name Millionate MR) 5 parts by weight Ethyleneimine cross-linking agent (manufactured by Nippon Shokubai Chemical Co., trade name TA
Z) 1 part by weight Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight Comparative Example 6 This example is an example in which no polyisocyanate compound was added.

First, 25 mol% of neopentyl glycol, 25 mol% of ethylene glycol, 25 mol% of terephthalic acid, and 25 mol% of isophthalic acid were reacted to synthesize a polyester resin A having a glass transition temperature of 65 ° C.

Then, an adhesive composition was obtained by mixing the following composition mainly composed of polyester resin A.

Polyester resin A 100 parts by weight Hydrophobic silica (Nippon Silica Co., Ltd., trade name Nipseal E2
00A-Methyltriethoxysilane treatment) 25 parts by weight Ethyleneimine-based cross-linking agent (Nippon Shokubai Kagaku Co., trade name TA
Z) 1 part by weight Toluene 150 parts by weight Methyl ethyl ketone 150 parts by weight The adhesive performance of each adhesive composition obtained in the above-mentioned Examples 1, 2 and Comparative Examples 1 to 6 was examined.

Sample preparation method First, the surface of the cold-rolled steel sheet with a thickness of 0.5 mm is degreased and washed, and then 1
% Chromic anhydride aqueous solution for 10 seconds, washed with water and dried. Then, the adhesive composition obtained in each of the above Examples and Comparative Examples was applied onto the steel plate subjected to the above-described treatment so that the coating thickness was about 4 μm, and dried at room temperature. Then, each sample plate was produced by heating in an electric oven at an ultimate plate temperature of 180 ° C. for 60 seconds, and then immediately laminating a semi-rigid vinyl chloride film by laminating at a linear pressure of 10 kg / cm.

The initial peel strength and the peel strength after 2 hours of the boiling water test were measured for each sample plate manufactured as described above by the following methods. The test method is as follows.

Initial peel strength: 20 ° C and 65% relative humidity one hour after bonding the vinyl chloride film and the steel sheet with the adhesive composition
Under the conditions described above, 180 degree peeling was performed at a speed of 50 mm / min, and the resistance when the vinyl chloride film peeled from the steel sheet was obtained.

Peeling strength after 2 hours of boiling water test: After immersing each sample plate in boiling water for 2 hours, 180 degree peeling was performed at a speed of 50 mm / min under the conditions of 20 ° C and 65% relative humidity, and chlorination from the steel plate was performed. The resistance when the vinyl film peels was determined.

The measurement results are shown in Table 1.

From the above results, the adhesive composition obtained by adding hydrophobic silica to the polyester resin having a glass transition temperature in the range of 50 to 80 ° C. is capable of low-temperature adhesion and exhibits good adhesion even after the boiling water test. I understand. In comparison, when the glass transition temperature of the polyester resin is outside the range of 50 to 80 ° C or when hydrophobic silica is not added, the adhesiveness deteriorates after the boiling water test, especially the glass transition of the polyester resin. In the case where the temperature exceeds 80 ° C. (Comparative Example 4) and the case where the amount of hydrophobic silica is too large (Comparative Example 3), the adhesiveness cannot be secured even in the initial stage.

Further, as shown in Comparative Example 6, it can be seen that the presence or absence of the addition of polyisocyanate has a great influence on the adhesiveness, and the adhesiveness is deteriorated in the absence of the addition.

Examples 3 to 5, Comparative Example 7 Then, various adhesive compositions were prepared by changing the addition amount of the polyisocyanate compound, and the initial peel strength and the peel strength after 2 hours of the boiling water test were measured in the same manner. . Table 2 shows the composition of each adhesive composition prepared (Examples 3 to 5 and Comparative Example 7). In each of these adhesive compositions, the polyester resin A is used as the polyester resin, and the polyisocyanate compound is manufactured by Nippon Polyurethane Co., Ltd. under the trade name Coronate C-2516 or Millionate.
MR, hydrophobic silica, manufactured by Nippon Silica Co., Ltd., trade name Nipseal SS50A, ethyleneimine-based crosslinking agent, manufactured by Nippon Shokubai Kagaku Co., Ltd., trade name TAZ (ω-aziridinylpropionic acid-2,2-dihydroxy) (Methyl butanol ester), and epoxy silane A-187 (trade name, manufactured by Nippon Unicar Co., Ltd.) was used as the silane coupling agent.

Table 3 shows the measurement results of the initial peel strength and the peel strength after 2 hours of the boiling water test.

From the above results, it can be seen that when the polyisocyanate compound is in the range of 10 to 50% by weight, good adhesion is exhibited both at the initial stage and after the boiling water test. When the content of the polyisocyanate compound is 50% by weight or more (Comparative Example 7), the peel strength after the boiling water test significantly decreases due to the influence of the unreacted polyisocyanate compound.

〔The invention's effect〕

As is clear from the above description, in the adhesive composition of the present invention, since the glass transition temperature uses a polyester resin having a temperature of 50 to 80 ° C., it is possible to perform low-temperature adhesion, for example, in an adherend. It is possible to maintain the commercial value of appearance without impairing the appearance of a vinyl chloride film. The glass transition temperature can be controlled by changing the combination of polyhydric alcohol and polybasic acid used in synthesizing the polyester resin and the synthesis ratio, and it is possible to synthesize a polyester resin having a predetermined glass transition temperature. .

Further, in the present invention, since the polyester resin having the above-mentioned predetermined glass transition temperature is used and the hydrophobic silica is added thereto, the hydrophobicity of the adhesive is improved and the adhesiveness can be secured even after the boiling water test. Since the water resistance can be remarkably improved and the polyisocyanate compound is added in a predetermined amount at the same time, the adhesive property of the adhesive composition is improved,
It is possible to greatly improve the peel strength.

Therefore, according to the present invention, it is possible to provide an adhesive composition capable of low-temperature adhesion, having high peel strength, and having excellent water resistance and adhesion reliability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-45376 (JP, A) JP-A-57-135822 (JP, A) JP-A-60-53576 (JP, A) JP-A-59- 71373 (JP, A) JP 60-8067 (JP, B2) JP 56-45952 (JP, B2)

Claims (1)

[Claims] 1. An adhesive composition for adhering a vinyl chloride film to a metal plate, comprising 50% by weight or more of a polyester resin having a glass transition temperature T _G of 50 to 80 ° C. and 5 to 50% by weight of hydrophobic silica, An adhesive composition comprising 0.1 to 50% by weight of a polyisocyanate compound.