KR19990061376A - Adhesive composition - Google Patents

Abstract

The present invention relates to an adhesive composition comprising an acrylic resin, 20 to 60 parts by weight of a ketone resin based on 100 parts by weight of the acrylic resin, and 3 to 5 parts by weight of an inorganic filler. Since the adhesive composition of the present invention can be transferred even at 120 ° C to 130 ° C, the productivity of the transfer process can be increased, and excellent adhesion and blocking properties can be obtained.

Description

Adhesive composition

In modern life, plastic cards are widely used in many fields, and plastic cards are mainly made of polyvinyl chloride (PVC).

Plastic cards are used as materials for printing, transparent holograms, magnetic stripes, writable pigments, and surface protection layers. All of the films (mainly polyester films having good heat resistance) are used as carriers, Functional layer, adhesive layer, and the like. A plastic card is produced by transferring the multilayered film to PVC using heat and pressure. The adhesive layer used in such a multilayer film should have a high adhesive strength to PVC and should be able to adhere at as low a temperature as possible and should not be transferred to the back side (opposite side) while being wound in a film (that is, And transparency is required when it is used for a transparent film such as a transparent hologram or a protective film.

It is important to properly control the adhesive strength and blocking resistance, which are the most important characteristics of the adhesive composition constituting the adhesive layer, as they are contradictory.

As a prior art method for increasing the adhesive strength and blocking resistance in the adhesive composition for producing a multilayer film, a method of releasing a coating on the back surface of the adhesive layer has been reported. However, There is a disadvantage that the manufacturing cost is increased due to the decrease. In addition, although a method of making the adhesive layer strong enough to be transferred only at a high temperature (150 ° C or higher) has been reported, this method has an advantage that blocking does not occur even without a backside release coating. On the other hand, There is a downside.

As described above, the adhesive compositions reported so far have problems in that the manufacturing cost is increased due to a decrease in productivity due to complicated processes, or the productivity of transcription companies is low due to high transcription temperature.

Accordingly, an object of the present invention is to provide a bonding composition which is capable of transferring at a low temperature, and is excellent in both adhesive strength and blocking resistance.

In order to achieve the above object, the present invention provides an adhesive composition comprising an acrylic resin, 20 to 60 parts by weight of a ketone resin based on 100 parts by weight of the acrylic resin, and 3 to 5 parts by weight of an inorganic filler.

Hereinafter, the present invention will be described in detail.

In the present invention, an acrylic resin is used as a main component of the adhesive composition, and as the acrylic resin, an MMA type, an MA type, an EMA type, a BMA type resin, or the like can be used, and an MMA type acrylic resin is preferable. The acrylic resin may be a resin having a glass transition temperature (Tg) of -10 to 110 ° C and an acid value of 0 to 20, a resin having a Tg of 30 to 70 ° C and an acid value of 0 to 15 . As the resin, MMA type copolymer having a Tg of 45 캜 and an acid value of 12, for example, Elvacite 2028 (ICI, UK) is most preferably used.

When MMA type of acrylic resin is used, it has low adhesive strength to PET film, good blocking resistance, good adhesion to PVC, and Tg of acrylic resin is related to bonding temperature and blocking. The lower the Tg, the lower the bonding temperature, but the easier the blocking, so it is important to adjust it properly.

The ketone resin is added to the composition for the purpose of improving blocking resistance and adhesion, and is used in an amount of 20 to 60 parts by weight, more preferably 30 to 50 parts by weight, based on 100 parts by weight of the acrylic resin. When the amount of the ketone-based resin is less than 20 parts by weight, blocking resistance is reduced. When the amount is more than 60 parts by weight, the adhesive strength is decreased. As the ketone-based resin, a resin having a glass transition temperature (Tg) of 0 to 110 ° C can be used, and it is preferable to use a synthetic ketone-based resin having a Tg of 30 to 110 ° C. In particular, it is most preferable to use Krumbhaar K1717B (Lawter Int., USA) having a Tg of 97 占 폚, which is advantageous for improving blocking resistance due to its high adhesive strength and high Tg.

The inorganic filler is added for the purpose of increasing the blocking resistance and is used in an amount of 3 to 5 parts by weight based on 100 parts by weight of the acrylic resin. When the amount of the inorganic filler is less than 3 parts by weight, blocking occurs. When the amount of the inorganic filler is more than 5 parts by weight, the adhesive strength is decreased. As the inorganic filler, those having a small particle size such as SiO ₂ , TiO ₂ and organic clay can be used, and those having a particle size of 0.1 to 0.5 μm can be used, and Nipsil E220A (particle size: 1.0 μ, manufactured by Nippon Silica) .

Since the shape of the surface of the adhesive layer varies depending on the choice of the solvent for dissolving the adhesive layer composition, the selection of the solvent also has a strong blocking effect. Since the solvent makes the dry surface of the resin slightly rough, it is preferable to use a solvent such as toluene, methanol, n-hexane, ethyl acetate, methyl ethyl ketone or a mixed solvent thereof to increase the blocking resistance. It is most preferable to use toluene / methanol / n-hexane in a ratio of 60/20/20 (v / v / v), but the mixing ratio thereof can be appropriately changed as needed. When the ratio of n-hexane is increased, the blocking resistance is increased, but the layer separation of the liquid (not a true solvent of the resin) occurs, and when the proportion of n-hexane is decreased, the blocking resistance is decreased but liquid stability is obtained.

The application amount of the adhesive layer made of the adhesive composition of the present invention is 0.5 to 1.0 g / m ² , preferably 0.8 g / m ² . ^. When the coating amount is less than 0.5 g / m ² , the blocking resistance is increased but the adhesive strength is decreased. When the coating amount is more than 1.0 g / m ² , the adhesive strength is increased but the blocking resistance is decreased and the manufacturing cost is increased.

The drying of the adhesive composition is preferably carried out at 100 to 140 캜 for 3 to 10 seconds as a condition capable of evaporating the solvent. If the drying temperature is lower than 100 ° C, drying is not likely to occur. If the drying temperature is higher than 140 ° C, the blocking will increase.

The adhesive composition of the present invention can be applied to any multilayer film in which an adhesive layer can be used. Also, since the composition of the present invention can be transferred at 120 ° C to 130 ° C, the productivity in the transfer process can be improved, and the adhesive strength and blocking resistance are excellent.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The physical properties of the adhesive layer in Examples and Comparative Examples were measured as follows.

≪ Property evaluation method &

① Transfer temperature

The adhesive composition was laminated to a PVC card to measure the temperature at which it was bonded.

② Adhesion

At the lowest transfer temperature, the side transferred to the PVC card was cross-hatched with a net width of 1 x 1 mm, and then peeled off with a tape to measure the degree of falling. The results were as follows.

Good: Good adhesion, less than 90% of the transfer surface

?: Middle of adhesion force, 90 to 50% of the transfer surface is not falling

X: poor adhesion, less than 50% of the transfer surface

③ My blocking ability

The finished product coated with the adhesive layer is allowed to stand for 24 hours in a thermo-hygrostat maintained at 60 ° C and 70% relative humidity in a wound state (in a state in which a plurality of films are stacked and pressure and tension are applied) Were visually observed and the results were expressed as follows.

○: Good blocking resistance, less than 10% of backside transfer occurred

?: Anti-blocking property Normally, about 10 to 50% of the backside transfer occurs

X: Bad blocking resistance, over 50% of backside transfer occurred.

≪ Examples 1 to 4 and Comparative Examples 1 to 3 >

In this Example, the adhesive composition having various compositions was applied to the adhesive layer of the protective film, and the physical properties thereof were measured.

A protective layer (a mixture of acrylic resin and wax) was coated on 19 占 of the polyester film and dried, and then various adhesive compositions having the composition shown in Table 1 were prepared and coated thereon. The application amount of the adhesive composition was 0.8 g / m ² , and the adhesive layer was dried at 120 ° C for 5 seconds. The produced film was evaluated according to the above evaluation method, and the results are shown in Table 2 below.

Composition of adhesive composition (unit: kg) Constituent Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Comparative Example 3 Comparative Example 4 Acrylic resin (Elvacite 2028) 10 10 10 10 10 10 10 Ketone series resin (Krumbhaar K1717B) 0.5 One 2 4 6 8 10 Inorganic filler (Nipsil E220A) 0.5 0.5 0.5 0.3 0.3 0.1 0 toluene 53 52.5 51.5 49.7 47.7 45.9 44 Methanol 18 18 18 18 18 18 18 n-hexane 18 18 18 18 18 18 18 Total amount 100 100 100 100 100 100 100

Evaluation results of physical properties of adhesive layer Properties Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Comparative Example 3 Comparative Example 4 Transfer temperature (캜) 110 110 120 120 130 130 130 My blocking ability △ △ ○ ○ ○ ○ ○ Adhesion ○ ○ ○ ○ ○ △ △

As can be seen from the results of Table 2, the adhesive layers of Comparative Examples 1 and 2 had poor blocking resistance and the adhesive layers of Comparative Examples 3 and 4 had poor adhesive strength. However, Blocking property and adhesive strength.

Since the adhesive composition of the present invention can be transferred even at 120 ° C to 130 ° C, the productivity of the transfer process can be increased, and excellent adhesion and blocking properties can be obtained.

Claims (7)

Acrylic resin, 20 to 60 parts by weight of a ketone resin based on 100 parts by weight of the acrylic resin, and 3 to 5 parts by weight of an inorganic filler. The method according to claim 1, Wherein the acrylic resin has a glass transition temperature (Tg) of 30 to 70 占 폚 and an acid value of 0 to 15. The method according to claim 1, Wherein the acrylic resin is Elvacite 2028 (ICI, UK). The method according to claim 1, Wherein the ketone-based resin has a glass transition temperature (Tg) of 30 to 110 占 폚. The method according to claim 1, Wherein the ketone resin is Krumbhaar K1717B (manufactured by Lawter Inc., USA). The method according to claim 1, Wherein the inorganic filler is SiO ₂ , TiO ₂ or organic clay having a particle size of 0.1 to 0.5 μm. The method according to claim 1, Wherein the inorganic filler is Nipsil E220A (manufactured by Nippon Silica Japan).