JPWO2009017160A1 - Adhesive composition - Google Patents

Abstract

The adhesive composition contains an elastomer having a solubility parameter of 18.5 MPa1 / 2 or less, a tackifier having a hydroxyl value of 20 mgKOH / g or more, and a near-infrared absorbing dye. The content of the tackifier is 100 parts by weight or more and 250 parts by weight or less with respect to 100 parts by weight of the elastomer. This adhesive composition has pressure-sensitive adhesiveness and good dye durability of the near-infrared absorbing dye.

Description

  The present invention relates to an adhesive composition that absorbs near infrared rays.

Pressure sensitive adhesives are widely used in electrical and electronic parts and other fields, and are used as adhesives for bonding many layered members such as plasma displays.
On the other hand, there is a near-infrared absorption filter that absorbs near-infrared light having a wavelength of 800 nm to 1100 nm as one of the layered members of the plasma display. This is provided in order to prevent malfunction of a remote control device or the like caused by near infrared rays, which are heat rays, being emitted from the screen.

  By the way, in the plasma display, in order to reduce the cost by reducing the weight or simplifying the manufacturing process, for example, an adhesive resin having a low glass transition point is used as a binder, and an adhesive layer is formed by dispersing a near-infrared absorbing dye therein. Thus, the adhesive layer has a function of a near-infrared absorbing filter, thereby reducing the materials used and the manufacturing process. In addition, as an adhesive composition for forming such an adhesive layer, a composition using a near-infrared absorbing dye such as an immonium dye and further containing a terpene phenol tackifier has been developed (for example, a patent). Reference 1).

JP 2004-182936 JP

  However, even when a near-infrared absorbing filter is formed using an adhesive composition in which a near-infrared absorbing dye is dispersed in a binder having a low glass transition point, the near-infrared absorbing dye is significantly deteriorated during aging and is difficult to put into practical use. In Patent Document 1, when a binder made of a (meth) acrylic polymer is used, the degradation of the near-infrared absorbing dye is suppressed by a device that keeps the hydroxyl value of the binder low. Absent. In order to prevent the deterioration of the near-infrared absorbing dye during aging, it may be possible to add a light stabilizer, but this increases the cost.

  Therefore, the present invention is an adhesive composition having pressure-sensitive adhesiveness and having near-infrared absorbing ability by containing a near-infrared absorbing dye, and the adhesive composition having good durability of the near-infrared absorbing dye The purpose is to provide goods.

  As a result of extensive research, the inventors of the present invention use an elastomer with a low solubility parameter, and use a high tackifier as a tackifier to prevent deterioration of the near-infrared absorbing dye. As a result, the present invention has been completed.

That is, the adhesive composition of the present invention contains an elastomer having a solubility parameter of 18.5 MPa ^1/2 or less, a tackifier having a hydroxyl value of 20 mgKOH / g or more, and a near-infrared absorbing dye. The imparting agent is contained in an amount of 10 to 250 parts by weight with respect to 100 parts by weight of the elastomer.

The adhesive composition of the present invention contains an elastomer having a solubility parameter of 18.5 MPa ^1/2 or less, a tackifier having a hydroxyl value of 20 mgKOH / g or more in a specific ratio, and further contains a near-infrared absorbing dye. Therefore, the dye durability of the near-infrared absorbing dye becomes good, and the transmittance of near-infrared light can be suppressed even after aging without adding a light stabilizer. It also has pressure sensitive adhesive properties due to the elastomer and tackifier.

  Hereinafter, the adhesive composition of the present invention will be described. Note that the present invention is not limited to the following description, and can be appropriately changed without departing from the spirit of the present invention.

  The adhesive composition of the present invention contains an elastomer, a tackifier, and a near infrared absorbing dye.

The elastomer contained in the adhesive composition of the present invention is a resin serving as a base of the adhesive composition, and has a solubility parameter (hereinafter referred to as SP value) of 18.5 MPa ^1/2 or less.

The SP value can be calculated from the Fedors equation shown in Equation 1 below. In the Fedors equation, “δ” is the SP value, “V” is the molar volume, and “E _coh ” is the binding energy.

This SP value indicates the degree of solubility of the elastomer in a polar solvent. In the adhesive composition of the present invention, since the SP value of the elastomer is a relatively low value of 18.5 MPa ^1/2 or less, the elastomer and the tackifier having a high hydroxyl value are not completely compatible. Although it is considered that the layers are locally separated, they are dispersed as a whole. Then, it is considered that the near-infrared absorbing dyes are prevented from associating and decomposing due to the hydroxyl group of the tackifier, and the deterioration of the near-infrared absorbing dyes is suppressed.

Here, if the SP value of the elastomer is larger than 18.5 MPa ^1/2 , the near-infrared absorbing dye is deteriorated, and the transmittance of near-infrared light having a wavelength in the vicinity of 800 nm to 1100 nm is greatly increased. On the other hand, if the SP value of the elastomer is too low, a tackifier having a hydroxyl value of 20 mgKOH / g or more is not compatible with the elastomer and the tackiness cannot be improved.

  Examples of such an elastomer include, but are not limited to, an elastomer made of styrene, isoprene, butylene, propylene, chloroprene, acrylonitrile, and the like. Specifically, for example, styrene-based elastomers such as styrene-ethylene-butylene-styrene rubber (SEBS), styrene-butadiene-styrene rubber (SBS), styrene-isoprene-styrene rubber (SIS) can be used. Examples include SEBS such as Quintac 3421 (manufactured by Zeon Corporation) and Septon 8007 (manufactured by Kuraray Co., Ltd.).

  Moreover, the tackifier contained in the adhesive composition of the present invention has a hydroxyl value of 20 mgKOH / g or more.

  Here, the hydroxyl value is the number of mg of potassium hydroxide (KOH) necessary for neutralizing acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated. This can be calculated according to the method described in JISK0070, or can be obtained as a theoretical value by calculation from the charged composition.

Conventionally, when a (meth) acrylic polymer was used as the base of an adhesive composition in order to prevent deterioration of the near-infrared absorbing dye, its hydroxyl value was kept low. In the composition, as described above, an elastomer having an SP value of 18.5 MPa ^1/2 or less is used as a base, and the tackifier is deteriorated in the near-infrared absorbing dye by setting the hydroxyl value to 20 mgKOH / g or more. Suppress.

  In the composition of the present invention, when the hydroxyl value of the tackifier is less than 20 mgKOH / g, the near infrared ray absorbing dye is deteriorated, which is not preferable.

  Examples of the tackifier having a hydroxyl value of 20 mgKOH / g or more include alkylphenol resins. Among the alkylphenol resins, those having a softening point of 25 ° C. or higher are preferable because durability of the near-infrared absorbing dye is improved. Specific examples of preferable alkylphenol resins include TH130, U130, T30 (all manufactured by Yasuhara Chemical Co., Ltd.) and the like.

  The content of the tackifier having a hydroxyl value of 20 mgKOH / g or more in the adhesive composition is 10 parts by weight or more and 250 parts by weight or less with respect to 100 parts by weight of the elastomer. Thereby, deterioration of a near-infrared absorption pigment | dye can be suppressed effectively. Moreover, preferable content of a tackifier is 15 to 100 weight part with respect to 100 weight part of elastomer. Thereby, peeling strength can also be improved.

  In order to adjust the tackiness of the adhesive composition, other tackifiers may be added to the adhesive composition of the present invention together with a tackifier having a hydroxyl value of 20 mgKOH / g or more. For example, a terpene resin such as Clearon M105 (manufactured by Yasuhara Chemical Co., Ltd.) may be added.

  The near-infrared absorbing dye contained in the adhesive composition of the present invention is a substance that absorbs near-infrared light having a wavelength of about 800 nm to 1100 nm. For example, cyanine dyes, phthalocyanine dyes, diimonium dyes, and the like can be used. . A single dye may be used, and a plurality of kinds may be appropriately combined in consideration of an absorption wavelength and durability, but it is preferable to contain at least a diimonium dye. Diimonium-based dyes have low absorption in the visible light region and strong absorption in the near infrared region. For example, in plasma displays that require absorption of light in the near infrared region, an adhesive layer that absorbs near infrared light This is useful when forming.

  Specific examples of near-infrared absorbing dyes include NK-8758 (produced by Hayashibara Biochemical Laboratories Co., Ltd.) as a cyanine dye, IR10A (produced by Nippon Shokubai Co., Ltd.) as a phthalocyanine dye, and IRG-022 (produced in Japan) as a diimonium dye. Kayaku Co., Ltd.).

  The adhesive composition of this invention can contain the solvent which disperse | distributes said elastomer, tackifier, and near-infrared absorption pigment | dye. Solvents that can be used here are not particularly limited as long as they can be uniformly dispersed. For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, propyl acetate, methanol, ethanol, isopropyl alcohol, toluene , Tetrahydrofuran, n-hexane, n-heptane, water and the like.

  The adhesive composition of the present invention may contain a softener, an antioxidant and the like as shown below.

  The softening agent is added for the purpose of adjusting fluidity and facilitating processing into a film, and any softening agent can be used as long as it softens the adhesive composition. It is added accordingly. As such a softening agent, for example, liquid paraffin, liquid rubber, polybutene, or the like can be used.

  Moreover, antioxidant is added in order to prevent oxidation of an adhesive composition, and is added as needed. As such an antioxidant, for example, a phenol-based antioxidant, a phosphite-based antioxidant, and a thioether-based antioxidant can be used, but the antioxidant is not limited thereto.

  Furthermore, in the present invention, light stabilizers such as ultraviolet absorbers and hindered amine light stabilizers, and other dyes such as neon cut dyes and visible toning dyes can also be added.

  The adhesive composition of the present invention containing such a substance can be formed as follows. First, the near-infrared absorbing dye is dissolved or uniformly dispersed in the solvent as described above. Then, an elastomer and a tackifier are mixed with this liquid. At this time, a softener, an antioxidant or the like is added as necessary.

  The adhesive composition formed in this manner can be used as an adhesive layer that adheres substrates to each other and has near-infrared absorption ability, for example, by applying the composition on a transparent substrate. Therefore, for example, in a field where a near-infrared absorbing filter is required as in a plasma display and a layered member needs to be bonded, the near-infrared absorbing filter can be separately obtained by using the adhesive composition of the present invention. There is no need to use it, and it becomes possible to provide a lightweight and inexpensive product.

  The method for applying the adhesive composition to the substrate is not particularly limited, and a known method can be used. For example, it may be applied directly to the base material, or may be applied in advance to a release paper and transferred to the base material after drying. In this case, the thickness of the adhesive composition applied to the substrate may be a thickness sufficient to absorb near-infrared rays, and is appropriately changed depending on the application.

  The dye durability and peel strength of the adhesive composition of the present invention will be described based on examples. In addition, as a near-infrared absorbing dye used in this Example, 0.5 part by weight of NK-8758 (manufactured by Hayashibara Biochemical Laboratories Co., Ltd.) as a cyanine dye and phthalocyanine with respect to 100 parts by weight of the base resin. A mixture of 1 part by weight of IR10A (manufactured by Nippon Shokubai Co., Ltd.) as a dye and 3 parts by weight of IRG-022 (manufactured by Nippon Kayaku Co., Ltd.) as a diimonium dye was used.

Example 1
First, the above infrared absorbing dye was dissolved in a mixed solvent of MEK and toluene. This solution was mixed with 100 parts by weight of Quintac 3421 (manufactured by ZEON CORPORATION) as a base resin and 20 parts by weight of an alkylphenol resin (TH130, manufactured by Yasuhara Chemical Co., Ltd.) as a tackifier. The adhesive composition prepared in this manner is a peelable polyester film, MD MD (# 38) (manufactured by Toray Film Processing Co., Ltd.) using a film applicator and having a resin film thickness after drying of 20 μm. ). After application, the sample was dried for 5 minutes in an oven at 100 ° C. The SP value of Quintac 3421, which is the base resin, is 17.3 MPa ^1/2 . Further, TH130 as a tackifier has a hydroxyl value of 56 mgKOH / g and a softening point of 130 ° C.

Example 2
An adhesive composition was prepared by increasing the amount of TH130 from 20 parts by weight of Example 1 to 50 parts by weight, and a sample was prepared in the same manner as in Example 1.

Example 3
An adhesive composition was prepared by increasing the amount of TH130 from 20 parts by weight of Example 1 to 100 parts by weight, and a sample was prepared in the same manner as in Example 1.

Example 4
An adhesive composition was prepared by increasing the amount of TH130 from 20 parts by weight of Example 1 to 50 parts by weight, and a sample was prepared in the same manner as in Example 1.

Example 5
An adhesive composition was prepared by adding TH130 in an amount of 15 to 15 parts by weight of Example 1, and further adding 40 parts by weight of Clearon M105 (Yasuhara Chemical Co., Ltd.), which is a terpene resin, as a tackifier. Samples were prepared in the same manner as in Example 1. In addition, the hydroxyl value of Clearon M105 which is terpene resin is 0 mgKOH / g, and a softening point is 105 degreeC.

Example 6
In the adhesive composition, the amount of TH130 was changed from 20 parts by weight to 15 parts by weight of Example 1, and further 40 parts by weight of Clearon M105 and 10 parts by weight of LIR200 (manufactured by Kuraray Co., Ltd.) which is a liquid isoprene rubber as a softening agent A sample was prepared in the same manner as in Example 1.

Example 7
An adhesive composition was prepared by increasing the amount of TH130 from 20 parts by weight of Example 1 to 250 parts by weight, and a sample was prepared in the same manner as in Example 1.

Example 8
An adhesive composition was prepared by using 100 parts by weight of Septon 8007 (manufactured by Kuraray Co., Ltd.) as an elastomer instead of the quintac 3421 of Example 1, and increasing the amount of TH130 to 50 parts by weight. Samples were prepared in the same manner as in Example 1. The SP value of Septon 8007, which is this base resin, is 18.1 MPa ^1/2 .

Example 9
An adhesive composition was prepared using 50 parts by weight of U130 (manufactured by Yasuhara Chemical Co., Ltd.) instead of TH130 of Example 1, and a sample was prepared in the same manner as in Example 1. U130 is an alkylphenol resin having a hydroxyl value of 25 mgKOH / g and a softening point of 130 ° C.

Example 10
An adhesive composition was prepared using 50 parts by weight of T30 (manufactured by Yasuhara Chemical Co., Ltd.) instead of TH130 of Example 1, and a sample was prepared in the same manner as in Example 1. T30 is an alkylphenol resin having a hydroxyl value of 56 mg KOH / g and a softening point of 30 ° C.

Comparative Example 1
An adhesive composition was prepared by reducing the amount of TH130 from 20 parts by weight of Example 1 to 2 parts by weight, and a sample was prepared in the same manner as in Example 1.

Comparative Example 2
An adhesive composition was prepared using 50 parts by weight of Clearon M105 instead of TH130 of Example 1, and a sample was prepared in the same manner as in Example 1.

Comparative Example 3
The following acrylic resin was manufactured as the base resin of the adhesive composition. That is, 120 parts of ethyl acetate was put into a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen gas introduction tube, heated to 65 ° C. under a nitrogen gas stream, BA) 40 parts, 2-ethylhexyl acrylate (2-EHA) 40 parts, methyl acrylate (MA) 16 parts, acrylic acid (AA) 4 parts, and azobisisobutyronitrile (AIBN) 0.25 parts. The mixture was added dropwise over 2 hours, and further maintained at the same temperature for 4 hours to obtain an acrylic resin having a nonvolatile content of 44.6% by weight. The average molecular weight of the obtained acrylic resin was about 850,000, the glass transition point (Tg) was −40 ° C., and the SP value was 19.8 MPa ^1/2 .

  The adhesive composition of this comparative example was prepared by using 100 parts by weight of the above-mentioned acrylic resin instead of Quintac 3421 of Example 1, without using a tackifier, and was prepared in the same manner as in Example 1. It was created.

Comparative Example 4
An adhesive composition was prepared using the acrylic resin produced in Comparative Example 3 in place of the base resin of Quintac 3421 in Example 1, and a sample was prepared in the same manner as in Example 1.

Comparative Example 5
The following acrylic resin was manufactured as the base resin of the adhesive composition. That is, 92 parts of methyl methacrylate (MMA) and 8 parts of methyl acrylate (MA) were used, and it was produced in the same manner as the acrylic resin shown in Comparative Example 3. The average molecular weight of the obtained acrylic resin was about 300,000, the glass transition point (Tg) was 95 ° C., and the SP value was 20.4 MPa ^1/2 .

  The adhesive composition of Comparative Example 5 was prepared by using 100 parts by weight of the above-mentioned acrylic resin instead of Quintac 3421 of Example 1, and was prepared without using a tackifier, and a sample was prepared in the same manner as in Example 1. It was created.

  With respect to each sample of Examples 1 to 10 and Comparative Examples 1 to 5 created as described above, and a sample after aging in which each sample was placed under conditions of 80 ° C. and 500 hours, a wavelength of 550 nm, The light transmittance was measured by irradiating light at 850 nm and 950 nm.

  Further, the peel strength between each sample and the adherend substrate was measured. In this measurement, first, the adhesive composition side surface of each sample prepared and 100 μm untreated polyethylene terephthalate (PET) film were laminated together with a hand roller, and then the therapy MD (# 38) which is an easily peelable film of each sample. ), And the sample surface after peeling and glass or PET as a substrate to be adhered are laminated with a hand roller, heated in an autoclave at 50 ° C. and 0.6 MPa for 1 hour, and returned to room temperature. A peel strength test sample was prepared. In Example 4, PET was used as an adherent substrate, and glass was used for adherend substrates in other Examples and Comparative Examples. The peel strength measurement conditions were a peel angle of 180 ° and a peel speed of 300 mm / min. The peel strength is preferably 3N / 2 cm or more practically, but even if it is smaller than that, it can be bonded to the extent that it can be bonded depending on the manner in which the base material and the adherend base are fixed to the frame. Can be used if there is sex.

Tables 1 to 3 below show the composition, transmittance, and peel strength of the adhesive compositions of Examples and Comparative Examples.

  The deterioration of the near-infrared absorbing dye can be judged by an increase in the transmittance of each sample. In the samples of Examples 1 to 10, it was found that the transmittance of light having wavelengths of 550 nm, 850 nm, and 950 nm hardly increased during aging, and the durability of the near-infrared absorbing dye was good. Such dye durability is good even when PET is used for the substrate to be adhered as in Example 4, and even when a terpene resin having a hydroxyl value of 0 mgKOH / g as in Example 5 is used, It was good even if a softener was used in combination as in Example 6. Further, as in Example 7, there was no effect on the dye durability even when the amount of the alkylphenol resin was large.

  Further, this dye durability was good even when other elastomers having different SP values were used as in Example 8. Furthermore, even if an alkylphenol resin having a relatively low hydroxyl value is used as a tackifier as in Example 9, or an alkylphenol resin having a low softening point is used as a tackifier as in Example 10, it is a dye. Durability was good.

  On the other hand, as in Comparative Example 1, when the amount of the alkylphenol resin was too small, an increase in transmittance was confirmed before aging, and it was found that the near-infrared absorbing dye deteriorated. Further, as in Comparative Example 2, when only a terpene resin having a hydroxyl value of 0 mgKOH / g was used as a tackifier, deterioration of the near-infrared absorbing dye was confirmed during aging.

  Further, as in Comparative Examples 3 to 5, when an acrylic resin having a high SP value was used as the base substrate, deterioration of the near-infrared absorbing dye was confirmed during aging regardless of the presence or absence of the alkylphenol resin. Note that the sample of Comparative Example 5 using an acrylic resin having a high glass transition temperature could not be bonded to the adherend substrate.

  Furthermore, as shown in Tables 1 to 3, the adhesive composition of the present invention also had good peel strength. Good peel strength can be obtained when the alkylphenol resin is 15 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the elastomer as in Examples 1 to 6, Example 9, and Example 10. I understood.

As described above, the adhesive composition of the present invention contains an elastomer having an SP value of 18.5 MPa ^1/2 or less and a tackifier such as an alkylphenol resin having a hydroxyl value of 20 mgKOH / g or more. An adhesive composition having excellent durability is obtained. The amount of the tackifier is preferably 10 parts by weight or more and 250 parts by weight or less with respect to 100 parts by weight of the elastomer, and further 15 parts by weight or more and 100 parts by weight with respect to 100 parts by weight of the elastomer. By setting it as the following, it becomes a favorable adhesive composition with high peel strength.

The present invention is useful for image display devices such as plasma displays and liquid crystal displays.

Claims (5)

An elastomer having a solubility parameter of 18.5 MPa ^1/2 or less;
A tackifier having a hydroxyl value of 20 mgKOH / g or more;
Containing a near-infrared absorbing dye,
The adhesive composition, wherein the tackifier is contained in an amount of 10 to 250 parts by weight with respect to 100 parts by weight of the elastomer.   The adhesive composition according to claim 1, wherein the tackifier is contained in an amount of 15 to 100 parts by weight with respect to 100 parts by weight of the elastomer.   The adhesive composition according to claim 1, wherein the tackifier is an alkylphenol resin.   The adhesive composition according to any one of claims 1 to 3, wherein the near-infrared absorbing dye contains at least a diimonium dye.   The adhesive composition according to any one of claims 1 to 4, wherein the elastomer is styrene-ethylene-butylene-styrene rubber.