JP2018199796A - Sealing material composition and sealing material - Google Patents

Abstract

To provide a sealing material composition having a predetermined thixotropy without adding a thixotropy imparting agent composed of an inorganic filler such as silica and an organic thickener such as amide wax.SOLUTION: A sealing material composition contains one or two or more monofunctional acryl monomers, a photoradical polymerization initiator, and a styrenic elastomer, as essential components, where, a three-dimensional distance calculated from a Hansen solubility parameter of the monofunctional acryl monomer and a Hansen solubility parameter of a soft segment in the styrenic elastomer is set within a predetermined range.SELECTED DRAWING: None

Description

  The present invention relates to a flexible sealing material that protects the electronic elements and the like from moisture and the like by applying to an electronic element and the like provided on an electronic substrate and the like, and sealing before the sealing material is cured The present invention relates to a material composition.

  2. Description of the Related Art Conventionally, a sealing material used for coating and protecting electronic devices and the like by applying a liquid sealing material composition to a substrate or the like and then curing it is known. Since this type of sealing material is liquid before being cured, it is easy to pour into the gap between the electronic elements, and has the merit that the electronic element can be reliably covered, but it is easy to flow out from the desired range. There is a problem that there is a possibility of covering even a portion to be exposed. Moreover, in a liquid sealing material composition, there exists a concern about the bad handling property, such as a foreign material being easy to adhere before hardening, and there exists a possibility of adhering to another member and becoming dirty. Regarding such a technique, for example, JP 2009-090231 A (Patent Document 1) discloses a liquid resin material that is cured by irradiation with light after being applied by a dispenser.

  In JP 2009-090231 A (Patent Document 1), in order to control the width and height when a liquid resin material is applied onto a substrate, inorganic filling such as silica is used in the liquid resin material to be used. Discloses a highly thixotropic liquid resin material containing 0.5 to 10% by mass of a thixotropic agent comprising an organic thickener such as an agent and an amide wax.

JP 2009-090231 A

  By the way, when a thixotropic agent comprising an inorganic filler such as silica is added to the encapsulant composition, there is a concern that the cured product becomes hard, transparency is lowered, and photocurability is adversely affected. Is done. On the other hand, the thixotropic agent comprising an organic thickener such as amide wax has a problem of compatibility depending on the compatibility with the resin to be added, and there is a concern about bleeding of the organic thickener.

The present invention has been made to solve the above problems. That is, when applied to an adherend to be sealed, the cured product is flexible and there is no concern about bleeding of the organic thickener while having a thixotropy that makes the sealing material composition difficult to spread. It aims at providing the sealing material which is a sealing material composition and its hardened | cured material.

The encapsulant and the encapsulant composition of the present invention that achieve the above object are configured as follows. That is, the encapsulant composition of the present invention is an encapsulant composition comprising one or more monofunctional acrylic monomers, a radical photopolymerization initiator, and a styrenic elastomer. When the Hansen solubility parameter of (δ _dl , δ _pl , δ _hl ) and the Hansen solubility parameter of the soft segment in the styrene elastomer are (δ _ds , δ _ps , δ _hs ), both of these solubility parameters (δ _dl , δ _pl , δ _hl ), (δ _ds , δ _ps , δ _hs ) (Equation 1)

  Is the three-dimensional distance Ra between the monofunctional acrylic monomer and the styrenic elastomer, and the three-dimensional distance Ra between the monofunctional acrylic monomer as a whole of the one or more monofunctional acrylic monomers and the styrenic elastomer is 6.4 to 7.8, and a three-dimensional distance Ra between at least one monofunctional acrylic monomer among the one or two or more monofunctional acrylic monomers and the styrenic elastomer is 7.6 or more. Alternatively, the encapsulant composition is characterized in that a thixo ratio of a mixture of two or more monofunctional acrylic monomers, the radical photopolymerization initiator, and the styrene elastomer is 4.2 or more.

The encapsulant composition is an encapsulant composition comprising one or more monofunctional acrylic monomers, a radical photopolymerization initiator, and a styrenic elastomer, wherein the Hansen solubility parameter of the monofunctional acrylic monomer (Δ _dl , δ _pl , δ _hl ) and the Hansen solubility parameter of the soft segment in the styrenic elastomer as (δ _ds , δ _ps , δ _hs ), these two solubility parameters (δ _dl , δ _pl) , δ _hl ), (δ _ds , δ _ps , δ _hs ) (Equation 1)

  Is the three-dimensional distance Ra between the monofunctional acrylic monomer and the styrenic elastomer, and the three-dimensional distance Ra between the monofunctional acrylic monomer as a whole of the one or more monofunctional acrylic monomers and the styrenic elastomer is 6.4 to 7.8, and the three-dimensional distance Ra between at least one monofunctional acrylic monomer among the one or two or more monofunctional acrylic monomers and the styrene elastomer is 7.6 or more. Therefore, a highly thixotropic sealing material composition can be obtained without adding a thixotropic agent or the like. That is, this encapsulant composition contains a monofunctional acrylic monomer having an appropriately large three-dimensional distance Ra, and the viscosity of the composition is different from the conventional one.

  More specifically, the encapsulant composition is a mixture of the one or more monofunctional acrylic monomers that are essential components in the composition, the photo radical polymerization initiator, and the styrene elastomer. The thixo ratio can be configured to be 4.2 or more. Therefore, it is a sealing material composition having high thixotropy in which the thixo ratio is 4.2 or more without adding a thixotropic agent or the like.

  In the conventional technology, in a sealing material composition in which a styrene elastomer is dissolved in an acrylic monomer, the concentration of the styrene elastomer is increased in order to increase the mechanical strength of the sealing material composition or to reduce moisture permeability. It was considered preferable. On the other hand, it has been said that if an acrylic monomer having a large difference in solubility parameter is used, the styrene elastomer is not dissolved. Therefore, based on this concept, the closer the solubility parameter of the styrene elastomer and the solubility parameter of the acrylic monomer that dissolves the styrene elastomer, the higher the solubility is expected. It is considered preferable to use a monomer.

  For example, Example 1 of JP2008-069302 discloses a composition containing 35 parts by mass of a styrene-isobutylene-styrene block copolymer and 95 parts by mass of isononyl acrylate as a monofunctional acrylic monomer. . The three-dimensional distance Ra of the solubility parameter in this composition is 6.3. In addition, in this example, 5 parts by mass of 2-ethyl-2-butylpropanediol diacrylate is included. However, since this is a bifunctional acrylic monomer, it does not correspond to the essential component of the present invention, but is calculated including this. The three-dimensional distance Ra is 6.3.

  As another example, in Example 1 of JP-A-2005-154528, 30 parts by mass of a styrene-isobutylene-styrene block copolymer, 100 parts by mass of n-stearyl acrylate as a monofunctional acrylic monomer, A composition comprising 8 parts by weight of boronyl acrylate is disclosed. The three-dimensional distance Ra of the solubility parameter in this composition is also 6.3. From these examples, it is considered difficult to select a monofunctional acrylic monomer having a three-dimensional distance Ra of 6.4 or more.

  In addition, in the said sealing material composition, although the three-dimensional distance Ra of the monofunctional acrylic monomer of the whole of 1 or 2 or more monofunctional acrylic monomers and the said styrene-type elastomer is 6.4-7.8, this 1 or The three-dimensional distance Ra of at least one monofunctional acrylic monomer among the two or more monofunctional acrylic monomers is 7.6 or more. This is because a predetermined thixotropy may not be obtained unless such a monofunctional acrylic monomer is included.

  The sealing material composition can comprise a styrene elastomer contained therein as a styrene-isobutylene-styrene block copolymer. Among styrene-based elastomers, styrene-isobutylene-styrene block copolymers have an isobutylene skeleton, so they are excellent in weather resistance and heat resistance, and thus improve the weather resistance and heat resistance of the encapsulant composition. , Moisture permeability can be lowered.

  The said sealing material composition can be comprised as a compounding ratio in the whole composition of the said styrene-type elastomer is 25 mass% or more. Since the blending ratio of the sealing material composition in the total composition of the styrene elastomer is 25% by mass or more, the weather resistance and heat resistance of the sealing material obtained by curing the sealing material composition are improved. The mechanical strength can be further increased.

  The said sealing material composition can be comprised as a thing whose viscosity in 25 degreeC is 10-1000 Pa.s. Since the sealing material composition has a viscosity at 25 ° C. of 10 to 1000 Pa · s, it can be easily applied to an adherend such as an electronic device by a dispenser.

  The sealing material composition includes the monofunctional acrylic monomer including the monofunctional acrylic monomer having the three-dimensional distance Ra of less than 7 and the monofunctional acrylic monomer having the three-dimensional distance Ra of more than 9. it can. Since the sealing material composition includes a monofunctional acrylic monomer having a three-dimensional distance Ra of less than 7, it is possible to easily increase the solubility of the styrene-based elastomer, and the monofunctional acrylic monomer having a three-dimensional distance Ra of more than 9. Therefore, the thixotropy of the sealing material composition can be easily improved.

  The said sealing material composition can be comprised as the said monofunctional acrylic monomer containing the 2 or more monofunctional acrylic monomer from which the said three-dimensional distance Ra leaves | separates 3 or more. Since the sealing material composition includes a mixture of a plurality of monofunctional acrylic monomers having a difference in three-dimensional distance of the monofunctional acrylic monomer of 3 or more, the solubility of the styrenic elastomer and the thixotropy of the sealing material composition Can increase the sex. However, when a monofunctional acrylic monomer having a three-dimensional distance difference exceeding 6 is included, it may be difficult for these monofunctional acrylic monomers to be compatible with each other. It is preferable to avoid the inclusion of a monofunctional acrylic monomer having a molecular weight exceeding 6.

  And this invention can be comprised as a sealing material which is a radical photocured hardened | cured material of one of the said sealing material compositions. Since the sealing material of the present invention is configured as a photo-radical polymerization cured product of any of the above-described sealing material compositions, it is difficult to cause dripping before being cured, and is flexible after curing and adheres to an adherend. Excellent protection against moisture and moisture.

  The sealing material composition of the present invention has thixotropy and is difficult to drip, and there is no concern about bleeding of the organic thickener. The sealing material of the present invention is flexible and can protect the adherend from moisture and the like.

  <Encapsulant composition>

  The present invention will be described in detail based on embodiments. The sealing material composition of the present invention comprises a monofunctional acrylic monomer, a radical photopolymerization initiator, and a styrene elastomer as essential components. Next, the components contained in the sealing material composition will be described.

Styrenic elastomer:
The styrene-based elastomer is a component that dissolves in the monofunctional acrylic monomer in the encapsulant composition, and increases the mechanical strength and lowers the moisture permeability after the monofunctional acrylic monomer is cured. Moreover, it is a component which provides rubber elasticity (flexibility) to a sealing material with a monofunctional acrylic monomer.

  From the viewpoint of imparting rubber elasticity to the sealing material, the hardness of the styrene-based elastomer is preferably A70 or less in terms of A hardness according to JIS K6253. It is because a softness | flexibility can be given to a sealing material by making hardness into A70 or less. Moreover, although the minimum of hardness is not provided in particular, it is preferable that it is A10 or more. An excessively flexible styrenic elastomer may contain many components such as plasticizers, which substantially increases the proportion of components other than the styrenic elastomer and the monofunctional acrylic monomer, resulting in adhesion and sealing. This is because there is a concern that the properties as a material may deteriorate.

  Since the styrene elastomer alone is a solid, it does not have adhesiveness at room temperature, but is uniformly dispersed in the encapsulant composition and the encapsulant by dissolving in the monofunctional acrylic monomer.

  The addition amount of the styrene-based elastomer is preferably 25 to 45% by mass in the sealing material composition, and more preferably 25 to 35% by mass. If the blend of styrene elastomer is less than 25% by mass, the mechanical strength may be lowered. On the other hand, when it exceeds 45 mass%, the viscosity of the encapsulant composition is increased, and application may be difficult. If it is 35 mass% or less, fluidity | liquidity is suitable and it is easy to apply | coat.

  Specific examples of the styrene elastomer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylenebutylene-styrene block copolymer (SEBS), and styrene. -Ethylene propylene-styrene block copolymer (SEPS), styrene-isobutylene-styrene block copolymer (SIBS) can be illustrated.

  Among these styrene elastomers, it is preferable to use a styrene-isobutylene-styrene block copolymer. This is because the styrene-isobutylene-styrene block copolymer has an isobutylene skeleton, so that it has excellent weather resistance and heat resistance, and in particular, can reduce moisture permeability.

In determining the sealing material composition of the present invention, the Hansen solubility parameters (δ _ds , δ _ps , δ _hs ) of the soft segment in the styrene elastomer are important.

The Hansen solubility parameter is a parameter proposed by Hansen, and the solubility parameter (δ _t ) proposed by Hildebrand is divided into three components. The Hildebrand solubility parameter (δ _t ) and the Hansen solubility parameter (δ _d , δ _p , δ _h ) have the following relationship.

δ _t ² = δ _d ² + δ _p ² + δ _h ² (Expression 2)

In the above (Formula 2), δ _d is a London dispersion force term, δ _p is a dipole force term, and δ _h is a hydrogen bond force term. The Hansen solubility parameter is a value unique to a substance and can be calculated from the chemical structure and composition ratio. It is known that the closer the values, the more compatible each other.

The solubility parameters (δ _d , δ _p , δ _h ) specifically shown below are values calculated from the chemical structure using van Krevelen & Hoftyzer method (DWvan Krevelen et al, Properties of Polymers 2nd Edition, (1976 )). There is also a document describing Hansen solubility parameters (Hansen Solubility Parameters: A User's Handbook, Second Edition (2007), by Charles M. Hansen).

The calculation of the Hansen solubility parameters (δ _ds , δ _ps , δ _hs ) of the soft segment in the styrene elastomer is performed by paying attention to the unit structure of the soft segment. The unit structure of the soft segment includes a butadiene structure, an isoprene structure, an ethylene-butylene structure, an ethylene-propylene structure, and an isobutylene structure, and Hansen solubility parameters are calculated for these. However, at this time, the double bond is calculated as cleaved. An example of the calculation result is as follows: butadiene structure (δ _ds = 16.0, δ _ps = 0, δ _hs = 0), isoprene structure (δ _ds = 15.8, δ _ps = 0, δ _hs = 0), Ethylene-butylene structure (δ _ds = 16.9, δ _ps = 0, δ _hs = 0), ethylene-propylene structure (δ _ds = 16.1, δ _ps = 0, δ _hs = 0), isobutylene structure (δ _ds = 17.1, δ _ps = 0, δ _hs = 0). If the styrene-based elastomer is a styrene-isobutylene-styrene block copolymer, the unit structure of the soft segment is isobutylene. Therefore, the Hansen solubility parameter of the soft segment in the styrene-isobutylene-styrene block copolymer is δ _ds = 17.1, δ _ps = 0, δ _hs = 0.

Monofunctional acrylic monomer:
The monofunctional acrylic monomer is a component for dissolving the styrene-based elastomer and mixing it uniformly in the encapsulant composition and the encapsulant. It is also a component for adhering to water and developing waterproofness. The monofunctional acrylic monomer is a low-viscosity liquid before curing, and is a component that cures by a photoradical reaction.

  The monofunctional acrylic monomer includes a monofunctional (meth) acrylamide monomer in addition to the monofunctional (meth) acrylic acid ester monomer. More specifically, aliphatic acrylate monomers, alicyclic acrylate monomers, ether acrylate monomers, cyclic ether acrylate monomers, hydroxyl group-containing acrylate monomers, aromatic acrylate esters. Monomers, carboxyl group-containing acrylate monomers, acrylamide monomers, aliphatic methacrylate monomers, alicyclic methacrylate monomers, ether methacrylate monomers, cyclic ether methacrylate monomers, hydroxyl group-containing methacrylate esters Monomers, aromatic methacrylate monomers, carboxyl group-containing methacrylate monomers, methacrylamide monomers, and the like. Moreover, it is preferable to use together an alicyclic acrylate monomer and an aliphatic acrylate monomer. By blending the alicyclic acrylate monomer, the adhesive residue of the sealing material can be increased and the adhesive residue can be reduced when the sealing material is peeled off. Moreover, there exists an effect which makes the sealing material after hardening tough and raises tensile strength. In addition, when the proportion of this component is increased, moisture resistance and transparency can be improved.

  Among the above examples, the aliphatic acrylate monomer can increase the flexibility of the encapsulant and greatly improve the elongation at break. Moreover, the solubility of a styrene-type elastomer can be improved. Specific examples of the aliphatic acrylate monomer include aliphatic hydrocarbon acrylic monomers such as lauryl acrylate, stearyl acrylate, isostearyl acrylate, decyl acrylate, and isodecyl acrylate. Lauryl acrylate is preferable because it is very excellent in solubility of styrene-based elastomers and is excellent in flexibility.

  Examples of alicyclic acrylate monomers include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyloxyethyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, 4-tert-butylcyclohexyl acrylate, and the like. Can be mentioned.

  Examples of ether-based acrylate monomers include butoxyethyl acrylate, ethoxydiethylene glycol acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, 2-ethylhexyl diglycol acrylate, 4-hydroxybutyl acrylate glycidyl ether, and nonylphenol ethylene oxide modified acrylate. .

  Examples of the cyclic ether acrylate monomer include tetrahydrofurfuryl acrylate.

  Examples of the hydroxyl group-containing acrylic acid ester monomer include 1,4-cyclohexanedimethanol monoacrylate, 2-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acrylate, and the like.

  Examples of aromatic acrylate monomers include phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, nonylphenol ethylene oxide-modified acrylate, benzyl acrylate, and the like.

  Examples of the carboxyl group-containing acrylic acid ester monomer include ω-carboxy-polycaprolactone monoacrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, and the like.

  Examples of acrylamide monomers include acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, hydroxyethylacrylamide, acroylmorpholine, and the like.

In determining the encapsulant composition of the present invention, the Hansen solubility parameters (δ _dl , δ _pl , δ _hl ) of the monofunctional acrylic monomer are also important. The Hansen solubility parameter of the monofunctional acrylic monomer is also a substance-specific value. If one monofunctional acrylic monomer is determined from the chemical structure and composition ratio, the Hansen solubility parameter (δ _dl , δ _pl , δ _hl ) should also be calculated. Can do.

When the monofunctional acrylic monomer is not single but is a mixture of two or more monofunctional acrylic monomers, the Hansen solubility parameter represents the ratio of each monofunctional acrylic monomer in volume%, and the ratio is expressed as the ratio of each monofunctional acrylic monomer. Calculated by adding the Hansen solubility parameter. For example, the monofunctional acrylic monomer 1 (solubility parameters (δ _d1 , δ _p1 , δ _h1 )) is 30% by volume, and the monofunctional acrylic monomer 2 (solubility parameters (δ _d2 , δ _p2 , δ _h2 )) is 70% by volume. The solubility parameters of the mixture (δ _dM , δ _pM , δ _hM )) are as follows:

δ _dM = 0.3 × δ _d1 + 0.7 × δ _d2
δ _pM = 0.3 × δ _p1 + 0.7 × δ _p2
δ _hM = 0.3 × δ _h1 + 0.7 × δ _h2

In the determination of the sealing material composition of the present invention, the Hansen solubility parameter (δ _ds , δ _ps , δ _hs ) of the soft segment in the styrene elastomer and the Hansen solubility parameter (δ _dl , δ _pl ) of the monofunctional acrylic monomer are determined. , δ _hl ), the three-dimensional distance Ra is calculated by (Equation 1). In the present specification and claims, for convenience of naming, the three-dimensional distance Ra thus determined is also referred to as a three-dimensional distance Ra between a monofunctional acrylic monomer and a styrene elastomer, or simply a three-dimensional distance Ra.

  In the present invention, a combination of a styrenic elastomer and a monofunctional acrylic monomer is used so that the three-dimensional distance Ra is in the range of 6.4 to 7.8. When the monofunctional acrylic monomer is a mixture of two or more monofunctional acrylic monomers, the three-dimensional distance Ra in at least one of the monofunctional acrylic monomers is 7.6 or more.

  If the three-dimensional distance Ra is less than 6.4, the styrene elastomer can be dissolved well and blended at a high concentration, but the thixotropy may be lowered. On the other hand, if the three-dimensional distance Ra exceeds 7.8, the styrenic elastomer may not be dissolved in the monofunctional acrylic monomer or may not be dissolved to a predetermined concentration.

  The tendency of the three-dimensional distance depending on the kind of the monofunctional acrylic monomer will be described. Aliphatic acrylate monomers tend to have a relatively small three-dimensional distance Ra. Many alicyclic acrylate monomers have a medium three-dimensional distance Ra. Many ether-based acrylate monomers have a three-dimensional distance Ra exceeding 7.8. Many cyclic ether acrylate monomers also have a large three-dimensional distance Ra. Many hydroxyl group-containing acrylic acid ester monomers have an extremely large three-dimensional distance Ra. Aromatic acrylic acid ester monomers often have a relatively large three-dimensional distance Ra. Carboxyl group-containing acrylate monomers often have very large three-dimensional distances Ra. Acrylamide monomers include those having a slightly large three-dimensional distance Ra to extremely large ones.

  Among the monofunctional acrylic monomers, when lauryl acrylate or stearyl acrylate is used alone, the styrene elastomer can be well dissolved and blended at a high concentration, but the thixotropy tends to be low. Aromatic acrylic ester monomers and acrylamide monomers can be effectively mixed with other monofunctional acrylic monomers to effectively improve thixotropy.

An example of the three-dimensional distance Ra of the styrene elastomer in which the unit structure of each monofunctional acrylic monomer and soft segment is isobutylene is as follows. Note that IB is an abbreviation for isobutylene.
Lauryl acrylate (δ _dl = 16.0, δ _pl = 1.8, δ _hl = 5.1) Three-dimensional distance from IB = 5.8
Stearyl acrylate (δ _dl = 14.8, δ _pl = 1.2, δ _hl = 4.2) Three-dimensional distance with IB = 6.3
Decyl acrylate (δ _dl = 16.8, δ _pl = 2.1, δ _hl = 5.5) Three-dimensional distance with IB = 6.0

Three-dimensional distance with IB of isobornyl acrylate (δ _dl = 15.6, δ _pl = 2.3, δ _hl = 5.8) = 6.9
Cyclohexyl acrylate (δ _dl = 17.8, δ _pl = 3.1, δ _hl = 6.7) Three-dimensional distance with IB = 7.5
Three-dimensional distance with dicyclopentanyl acrylate (δ _dl = 15.9, δ _pl = 2.5, δ _hl = 6.0) IB = 6.9
Dicyclopentenyloxyethyl acrylate (δ _dl = 15.9, δ _pl = 2.8, δ _hl = 6.6) Three-dimensional distance to IB = 7.6

Ethoxydiethylene glycol acrylate (δ _dl = 17.1, δ _pl = 4.3, δ _hl = 8.7) Three-dimensional distance from IB = 9.7
2-ethylhexyl diglycol acrylate (δ _dl = 17.7, δ _pl = 2.9, δ _hl = 7.1) three-dimensional distance to IB = 7.8
Butoxyethyl acrylate (δ _dl = 15.8, δ _pl = 3.5, δ _hl = 7.4) Three-dimensional distance from IB = 8.6
Three-dimensional distance from phenoxyethyl acrylate (δ _dl = 18.7, δ _pl = 3.7, δ _hl = 7.6) IB = 9.1
4-hydroxybutyl acrylate glycidyl ether (δ _dl = 16.3, δ _pl = 4.0, δ _hl = 8.3) Three-dimensional distance from IB = 9.3

Tetrahydrofurfuryl acrylate (δ _dl = 16.7, δ _pl = 4.3, δ _hl = 8.3) Three-dimensional distance with IB = 9.4

1,4-cyclohexanedimethanol monoacrylate (δ _dl = 16.9, δ _pl = 3.7, δ _hl = 12.0) three-dimensional distance from IB = 12.6
2-hydroxybutyl acrylate (δ _dl = 16.2, δ _pl = 5.1, δ _hl = 14.0) Three-dimensional distance with IB = 15.0
2-hydroxypropyl acrylate (δ _dl = 16.0, δ _pl = 5.7, δ _hl = 14.8) three-dimensional distance with IB = 16.0
2-hydroxyethyl acrylate (δ _dl = 17.7, δ _pl = 7.1, δ _hl = 16.6) Three-dimensional distance with IB = 18.1

Three-dimensional distance with benzyl acrylate (δ _dl = 18.8, δ _pl = 3.3, δ _hl = 6.8) IB = 8.3

2-acryloyloxyethyl succinic acid (δ _dl = 17.1, δ _pl = 4.6, δ _hl = 11.7) three-dimensional distance from IB = 12.6

Three-dimensional distance to acrylamide (δ _dl = 18.5, δ _pl = 12.2, δ _hl = 12.8) IB = 17.9
N, N-dimethylacrylamide (δ _dl = 17.1, δ _pl = 10.8, δ _hl = 8.3) Three-dimensional distance to IB = 13.6
N, N-diethylacrylamide (δ _dl = 16.7, δ _pl = 8.1, δ _hl = 7.1) 3D distance from IB = 10.8
Three-dimensional distance of hydroxyethyl acrylamide (δ _dl = 17.5, δ _pl = 9.2, δ _hl = 15.6) IB = 18.1
Acroylmorpholine (δ _dl = 18.1, δ _pl = 9.4, δ _hl = 8.9) 3D distance from IB = 13.1

  As the monofunctional acrylic monomer, a single monofunctional acrylic monomer can be used, but it is preferable to use a mixture of a plurality of monofunctional acrylic monomers. A single monofunctional acrylic monomer may not dissolve the styrene-based elastomer, or may be one that does not fall within the preferred range of 6.4 to 7.8 as indicated by the above-mentioned three-dimensional distance value. This is because these problems can be solved by mixing with the monofunctional acrylic monomer. Moreover, it is because the good balance of the solubility of styrene-type elastomer and high thixotropy can be improved further by mixing the monofunctional acrylic monomer which has several different solubility parameters.

  For example, a monofunctional acrylic monomer having a three-dimensional distance Ra of less than 7 and a monofunctional acrylic monomer having a three-dimensional distance Ra of more than 9 are mixed so that the three-dimensional distance Ra is 6.4 to 7.8. It is preferable to use a mixture in which the blending amounts of both monofunctional acrylic monomers are adjusted. Comparing the case where a mixture of a plurality of monofunctional acrylic monomers having the same three-dimensional distance Ra is used and the case of using a single monofunctional acrylic monomer, the three-dimensional distance Ra is less than 7 in the case of a mixture. Since the monofunctional acrylic monomer is included, the solubility of the styrene-based elastomer is easily improved, and the monofunctional acrylic monomer having a three-dimensional distance Ra exceeding 9 is included, so that there is an advantage that the thixotropy is easily increased.

  When a plurality of monofunctional acrylic monomers are used, the three-dimensional distance Ra1 of the Hansen solubility parameter of the soft segment in the styrene elastomer of one monofunctional acrylic monomer and the styrene elastomer of the other monofunctional acrylic monomer The difference from the Hansen solubility parameter of the soft segment to the three-dimensional distance Ra2 is preferably 3 or more and 6 or less.

  By using a mixture of monofunctional acrylic monomers having a three-dimensional distance difference of 3 or more, the solubility of the styrenic elastomer can be further enhanced, and the thixotropy of the encapsulant composition can be further enhanced. However, when the difference in the three-dimensional distance exceeds 6, these monofunctional acrylic monomers are difficult to be compatible with each other, so that the above effects may not be exhibited over a long period of time.

  It is preferable that the addition amount of a monofunctional acrylic monomer is 55-75 mass% in a sealing material composition and a sealing material. If it is less than 55% by mass, the viscosity of the encapsulant composition may be too high, and if it exceeds 75% by mass, the mechanical strength of the encapsulant may be lowered. In 55-75 mass%, it is preferable to make it a small quantity in the possible range.

  The bifunctional or higher acrylic monomer can be used in a small amount for the purpose of adjusting the hardness or reducing the surface tack, but is not an essential component of the present invention. When a bifunctional or higher functional acrylic monomer is blended, the content is preferably 5% by mass or less, more preferably 1% by mass or less in the encapsulant composition and the encapsulant. This is because when added in a large amount, there is a concern about an increase in hardness and a decrease in adhesiveness.

Photo radical polymerization initiator:
The radical photopolymerization initiator is a substance that is cured by photoreacting a monofunctional acrylic monomer. After apply | coating a sealing material composition on an electronic device, it can be set as the sealing material which improved the adhesiveness with respect to an electronic device by photocuring a monofunctional acrylic monomer. Examples of the photoradical polymerization initiator include benzophenone-based, thioxanthone-based, acetophenone-based, and acylphosphine-based photopolymerization initiators. The addition amount of the photo radical polymerization initiator is preferably 0.1 to 10 parts by weight, more preferably 1 to 8 parts by weight with respect to 100 parts by weight of the total amount of all acrylic monomers including monofunctional and bifunctional or more preferable.

Other ingredients:
Various additives can be appropriately blended without departing from the spirit of the present invention. For example, a silane coupling agent, a polymerization inhibitor, an antifoaming agent, a light stabilizer, an antioxidant, an antistatic agent, a filler and the like can be mentioned.

  Since the present invention is characterized in that a predetermined thixotropy can be obtained without adding a thixotropic agent, it is preferable that the thixotropic agent is not completely contained. It does not exclude that a thixotropic agent is contained in the stopping material. Even if it contains a thixotropic agent, it is preferable that it is not much, so it can be contained in the encapsulant composition or encapsulant in an amount of less than 2 mass%, more preferably less than 0.5 mass%.

  The encapsulant composition is prepared by mixing a radical radical polymerization initiator, a styrenic elastomer, and various additives as necessary with one or more monofunctional acrylic monomers and stirring the styrenic elastomer into the monofunctional acrylic monomer. It can be produced by dissolving in a monomer.

  Next, the properties of the sealing material composition will be described. The sealing material composition is a liquid composition having a predetermined thixotropy. That is, since it is a liquid composition, it can be applied to an adherend such as an electronic device by a dispenser and has thixotropy, so that it stays within the applied range and flows out of the range. It is hard to wake up.

  From the viewpoint of applying the sealing material composition to an electronic device or the like, the viscosity of the sealing material composition is preferably 10 to 1000 Pa · s at 25 ° C., more preferably 20 to 300 Pa · s. When the viscosity is less than 10 Pa · s, not only dripping is likely to occur, but the content of styrene-based elastomer is small and the mechanical strength and low moisture permeability may not be sufficient. On the other hand, when it exceeds 1000 Pa · s, application by a dispenser becomes difficult. In addition, when it is 20 Pa · s or more, shape retention is improved from application to curing, and when it is 200 Pa · s or less, fine dispensing using a thinner needle is possible. The viscosity can be a value measured at a rotational speed of 10 rpm and a measurement temperature of 25 ° C. using a B-type rotational viscometer.

  The viscosity can be adjusted by the molecular weight and blending amount of the styrene elastomer, the kind of monofunctional acrylic monomer, and the like. In order to reduce the viscosity of the sealing material composition, it is preferable to use a monofunctional acrylic monomer having a three-dimensional distance of less than 7 and a low viscosity. Examples of this type of monofunctional acrylic monomer include low-viscosity aliphatic monofunctional acrylic monomers such as lauryl acrylate and isononyl acrylate.

  The thixotropy is a property that the viscosity changes depending on the difference in shear rate. The viscosity varies depending on the shear rate, but the higher the ratio between the high viscosity when the shear rate is low and the low viscosity when the shear rate is high, the higher the thixotropy. The higher the thixotropy is, the easier it is to apply, but the more difficult it is to cause dripping. Therefore, the high thixotropy is one of the features of the present invention. In the present invention, the ratio (viscosity (1 rpm) / viscosity (10 rpm)) of the viscosity measured under the condition of a rotational speed of 1 rpm in the environment of 25 ° C. and the rotational speed of 10 rpm as the thixo ratio. Calculated and used as an index of thixotropy.

  If the thixo ratio of the encapsulant composition is 4.2 or more, the applied encapsulant composition can be prevented from spreading before curing, and the encapsulant composition of the present invention is The thixo ratio can be 4.2 or more. On the other hand, the upper limit is not limited, but is preferably about 20 or less.

  Such a sealing material composition of the present invention hardly flows and spreads after the application, and can be kept within a predetermined applied range. For this reason, it is difficult to flow out of the periphery of the application target to be contaminated or to reduce the thickness of the sealing material on the application target, so that a desired protective effect for the adherend can be obtained.

  The sealing material composition of the present invention can be composed of only one or two or more monofunctional acrylic monomers, a radical photopolymerization initiator, and a styrene elastomer. Even if it contains, the thixotropic property imparting agent which consists of organic thickeners, such as inorganic fillers, such as a silica, and an amide wax, may not be included. Therefore, the flexibility of the cured product can be increased, and the transparency can be increased if necessary. Moreover, it can be set as the sealing material composition without the bleeding of an organic thickener.

  In the sealing material composition of the present invention, when applied with a dispenser or the like, it exhibits a relatively high shear rate when applied, and thus exhibits a low viscosity. It will show viscosity. For this reason, it shows high fluidity at the time of application and is easy to apply. Therefore, it is easy to keep the encapsulant composition within a predetermined range before curing.

  <Encapsulant>

  The sealing material is obtained by photocuring the acrylic monomer in the sealing material composition. That is, an encapsulant composition is applied to an electronic element provided on an electronic substrate or the like or a portion where a metal is exposed to cover an adherend, and then the encapsulant composition is used as an encapsulant by light irradiation.

  The sealing material is a flexible rubber-like elastic body, and the storage elastic modulus E ′ measured with a dynamic viscoelasticity measuring device is preferably in the range of 0.01 to 100 MPa. If the storage elastic modulus E ′ is less than 0.01 MPa, the mechanical strength may be reduced, and if it exceeds 100 MPa, the flexibility when mounted on a flexible adherend such as a flexible electronic substrate. There is a risk of damage.

  Such a sealing material has an adhesive force derived from an acrylic monomer, and can be in close contact with an adherend to prevent entry of foreign matter and moisture.

  As the sealing material, in addition to the sealing material obtained by curing the sealing material composition, a cured material of the sealing material composition provided with a reinforcing layer may be used as the sealing material. Examples of the reinforcing layer include those obtained by adjusting the hardness of the same type of composition as the sealing material composition, urethane films, other resin films, meshes, and the like. When laminating such a reinforcing layer, it is provided on the surface of the sealing material opposite to the surface to be adhered to an adherend such as an electronic substrate.

  As a method for providing the reinforcing layer, a liquid composition to be a sealing material composition and a liquid composition to be a reinforcing layer are applied in order, and then both are cured and adhered, or a sealing material composition is used. A method of curing a sealing material composition after laminating a reinforcing film or the like after coating can be employed. In this case, the reinforcing film needs to transmit ultraviolet rays and is preferably transparent.

  The above-described embodiment is an exemplification of the present invention, and modifications of the embodiment, addition of known techniques, combinations, and the like can be made without departing from the spirit of the present invention, and these techniques are also within the scope of the present invention. Is included.

  For example, the curing means for the encapsulant composition is not limited to ultraviolet rays, and may be visible light, electron beam, or the like. In that case, a radical generator corresponding to the wavelength of the energy beam to be irradiated may be added. When the electron beam is irradiated, the (meth) acryloyl group can be directly activated.

  Next, the present invention will be described in more detail based on examples (comparative examples). The encapsulant composition and encapsulant of the following samples 1 to 13 were produced.

<Preparation of sample>

Sample 1:
As monofunctional acrylic monomer, lauryl acrylate (aliphatic acrylate monomer) and isobornyl acrylate (alicyclic acrylate monomer) are prepared, and styrene elastomer is styrene-isobutylene-styrene having a hardness of A25. A block copolymer (SIBS) was prepared. Styrene elastomer was added to the monofunctional acrylic monomer and stirred for 24 hours to dissolve the styrene elastomer in the monofunctional acrylic monomer. The blending ratio at this time was adjusted to be 35% by mass of lauryl acrylate, 35% by mass of isobornyl acrylate, and 30% by mass of styrene elastomer. Then, a mass component in which 2-hydroxy-2-methyl-1-phenylpropan-1-one, which is a photoradical polymerization initiator, is 5 mass% is added to the total mass of the monofunctional acrylic monomer, and Sample 1 is added. An encapsulant composition was obtained. Then, the sealing material of sample 1 was obtained by irradiating with ultraviolet rays under the conditions of illuminance of 600 mW / cm ² and integrated light quantity of 5000 mJ / cm ² .

Samples 2-13:
The sealing material compositions of Samples 2 to 13 were prepared in the same manner as Sample 1 except that the styrene elastomer and monofunctional acrylic monomer of Sample 1 were changed to the types and blends (% by mass) shown in Tables 1 and 2. did. Monofunctional acrylic monomers other than those used above were dicyclopentenyloxyethyl acrylate (monofunctional alicyclic acrylate monomer), phenoxyethyl acrylate (monofunctional aromatic ether acrylate monomer), 4- Hydroxybutyl acrylate glycidyl ether (monofunctional ether-based acrylate monomer), N, N-diethylacrylamide (monofunctional acrylamide-based monomer), acroylmorpholine (monofunctional acrylamide-based monomer), 1,4-cyclohexanedimethanol mono It is an acrylate (monofunctional hydroxyl group-containing acrylic ester monomer), and the styrene elastomer is a styrene-ethylenepropylene-styrene block copolymer (SEPS, hardness A36). However, for sample 11, silica (thixotropic agent, hydrophilic fumed silica having a specific surface area of about 200 m ² / g) with respect to a total of 100 parts by mass of the styrene elastomer and monofunctional acrylic monomer listed in Table 2. 10 parts by mass). The sealing material compositions of Samples 2 to 13 were irradiated with ultraviolet rays in the same manner as Sample 1, and the sealing materials of Samples 2 to 13 were obtained.

  <Various tests and evaluation>

Hansen solubility parameter and three-dimensional distance Ra:
The solubility parameters (δ _ds , δ _ps , δ _hs ) of the styrene elastomer soft segment of each sample) and the Hansen solubility parameters (δ _dl , δ _pl , δ _hl ) of the monofunctional acrylic monomer of each sample Calculated by Further, the three-dimensional distance Ra was calculated based on the above (Equation 1). These results are shown in the table. The table shows the three-dimensional distance Ra of each monofunctional acrylic monomer with respect to the styrenic elastomer used in each sample in the “monofunctional acrylic monomer (single)” column, as well as 3 for all monofunctional acrylic monomers. The dimensional distance Ra is shown in the “monofunctional acrylic monomer (mixture)” column. In addition, in some cases, “o” or “no” indicates whether or not there is a three-dimensional distance Ra of at least one monofunctional acrylic monomer of 7.6 or more among a plurality of monofunctional acrylic monomers used in each sample. The case was entered as “x” in the “Existence of Ra ≧ 7.6 alone” column.

Styrenic elastomer solubility:
The properties after 24 hours were confirmed by continuing to stir the encapsulant composition of each sample. “◯” indicates that the styrene-based elastomer was dissolved in the monofunctional acrylic monomer and was entirely liquid, and “X” indicates that the styrene-based elastomer did not dissolve at all or was swollen. The results are also shown in the table.

viscosity:
About the sealing material composition of each sample, spindle No. was measured with a viscometer (BROOK FIELD's rotational viscometer DV-E). Using 14 rotors, the viscosity was measured under the conditions of rotation speeds of 1 rpm and 10 rpm and a measurement temperature of 25 ° C. The results are also shown in the table. In addition, the value measured at 10 rpm shall be a representative value of the viscosity of each sample.

Thix ratio:
The ratio of the viscosity at a rotational speed of 1 rpm obtained by the above viscosity measurement and the viscosity at a rotational speed of 10 rpm (viscosity (1 rpm) / viscosity (10 rpm)) was calculated to obtain a thixo ratio. The results are also shown in the table.

Visible light transmittance:
About each sample, a sealing material is formed in a flat plate shape with a thickness of 1 mm to obtain a test piece for transmittance measurement, and this test piece is used using an ultraviolet-visible spectrophotometer (“UV-1600” manufactured by Shimadzu Corporation). The parallel transmittance of was measured. And the average transmittance | permeability between wavelength 380nm -780nm was calculated | required based on the measurement result. The results are also shown in the table.

Rubber hardness:
About the sealing material of each sample, the hardness was measured using the type A durometer according to JISK6253 prescription | regulation. The results are also shown in the table.

  <Analysis of test results>

  Sample 1 having a three-dimensional distance Ra of 6.3 between the solubility parameter of the soft segment of the styrene-based elastomer and the solubility parameter of the monofunctional acrylic monomer mixture has a thixo ratio of 2.9, and the three-dimensional distance Ra is also 6.3. Sample 9 had a thixo ratio of 2.1, which resulted in a composition with low thixotropy. On the other hand, Sample 2 to Sample 7, Sample 12, and Sample 13 in which the three-dimensional distance Ra was in the range of 6.4 to 7.8 had a thixotropy of 4.2 or more and became a highly thixotropic composition. From the above, it has been found that when the three-dimensional distance Ra is adjusted to the range of 6.4 to 7.8, a sealing material composition capable of dissolving the styrene-based elastomer and having a large thixo ratio can be obtained. Sample 8 had a high three-dimensional distance Ra of 8.1, but did not dissolve the styrene elastomer. Sample 11 was a sample in which a thixotropic agent was mixed, although the thixo ratio was as high as 7.7 although the three-dimensional distance Ra was as low as 6.3.

  Samples 9 and 10 in which the type of styrene elastomer was changed from a styrene-isobutylene-styrene block copolymer (SIBS) having a hardness of A25 to a styrene-ethylenepropylene-styrene block copolymer (SEPS) having a hardness of A36 , The sample 9 having a three-dimensional distance Ra of 6.3 has a low thixo ratio of 2.1, and the sample 10 having a three-dimensional distance Ra of 6.7 has a high thixo ratio of 7.1. From this, it has been found that the relationship between the three-dimensional distance Ra and the thixo ratio shows the same tendency for styrene-based elastomers even when SEPS is used instead of SIBS. Also, compared with Sample 4 where the amount of addition of this sample 10 and styrene-based elastomer is the same, the hardness that was A12 in Sample 4 was reduced to A8 in Sample 10, so SEPS was used instead of SIBS. It was found that the hardness can be reduced.

  Sample 11 to which the thixotropic agent was added had a three-dimensional distance Ra of 6.3, and the Ra value was the same as Sample 1, but the thixo ratio was as large as 7.7. That is, even if the three-dimensional distance is out of the range of 6.4 to 7.8, the thixo ratio is improved by adding the thixotropic agent. However, in sample 11, the viscosity increased considerably to 611 Pa · s, and the visible light transmittance, which was 29% in sample 1, decreased to 10%. On the other hand, in sample 3, which has a thixo ratio substantially similar to that of sample 11 to which the thixotropic agent is added, the increase in viscosity is up to 403 Pa · s, the visible light transmittance is 72%, and the visible light transmittance is rather high. It has become. From the above results, in the present invention that does not contain a thixotropic agent, the three-dimensional distance is 6.4 to 7.8 without causing problems such as an increase in viscosity and a decrease in visible light transmittance caused by the addition of the thixotropic agent. It was found that an appropriate thixo ratio can be obtained by adjusting the type of the monofunctional acrylic monomer so that it falls within the range of.

  Regarding the blending ratio of styrene-based elastomer (SIBS), the thixo ratio of the sample 12 containing 19% by mass is 4.2, and the sample 13 containing 25% by mass increases the thixo ratio to 5.4, and further contains 30% by mass. In 2, the thixo ratio increased to 7.1. From this, it was found that when the proportion of the styrene-based elastomer was decreased, the thixo ratio was also decreased, and the content of the styrene-based elastomer was preferably 25% by mass or more, more preferably 30% by mass or more.

Claims (7)

An encapsulant composition comprising one or more monofunctional acrylic monomers, a radical photopolymerization initiator, and a styrenic elastomer,
When the Hansen solubility parameter of the monofunctional acrylic monomer is (δ _dl , δ _pl , δ _hl ) and the Hansen solubility parameter of the soft segment in the styrene elastomer is (δ _ds , δ _ps , δ _hs ), From the solubility parameters (δ _dl , δ _pl , δ _hl ), (δ _ds , δ _ps , δ _hs ) (Equation 1)

If Ra is calculated as a three-dimensional distance Ra between the monofunctional acrylic monomer and the styrene elastomer,
The three-dimensional distance Ra between the monofunctional acrylic monomer of the whole of the one or more monofunctional acrylic monomers and the styrene elastomer is 6.4 to 7.8,
The three-dimensional distance Ra between at least one monofunctional acrylic monomer of the one or two or more monofunctional acrylic monomers and the styrenic elastomer is 7.6 or more,
The encapsulant composition, wherein the thixo ratio of the mixture of the one or more monofunctional acrylic monomers, the radical photopolymerization initiator, and the styrene elastomer is 4.2 or more.
The encapsulant composition according to claim 1, wherein the styrene elastomer is a styrene-isobutylene-styrene block copolymer.
The encapsulant composition according to claim 1 or 2, wherein a blending ratio of the styrene-based elastomer in the entire composition is 25% by mass or more.
The sealing material composition according to any one of claims 1 to 3, wherein the viscosity at 25 ° C is 10 to 1000 Pa · s.
The monofunctional acrylic monomer includes a monofunctional acrylic monomer having the three-dimensional distance Ra of less than 7 and a monofunctional acrylic monomer having the three-dimensional distance Ra of more than 9. 5. The sealing material composition according to item.
The encapsulant composition according to any one of claims 1 to 4, wherein the monofunctional acrylic monomer includes two or more monofunctional acrylic monomers whose three-dimensional distance Ra is separated by 3 or more.
The sealing material which is the radical photopolymerization hardened | cured material of the sealing material composition in any one of Claims 1-6.