Interlayer film for laminated glass
Provided is an interlayer film for laminated glass which is excellent in sound insulation property and has improved sound insulation performance not only in a coincidence region but also in a mass-dominated region. The interlayer film for laminated glass includes a sound insulating layer which is formed from a composition (A) containing at least one resin (a1) selected from a thermoplastic resin and a thermosetting resin, wherein a tan δ obtained when a dynamic viscoelasticity of a sheet, which is obtained by molding the composition (A) to have a thickness of 0.8 mm, is measured at a frequency of 0.3 Hz in a tension mode has a maximal value at a temperature T A (° C.), T A (° C.) is in a range of −50 to 50° C., and the tan δ at T A (° C.) is 2.5 or more.
1. An interlayer film comprising a sound insulating layer which is formed from a composition (A) comprising:
at least one thermoplastic resin (a1); and
a compound (a2) having at least two ring structures and having a condensed ring skeleton;
wherein the thermoplastic resin (a1) is selected from the group consisting of a polyvinyl acetal, a polyvinyl carboxylate, and an olefin-vinyl carboxylate copolymer,
wherein a tan δ obtained when a dynamic viscoelasticity of a sheet, which is obtained by molding the composition (A) to have a thickness of 0.8 mm, is measured at a frequency of 0.3 Hz in a tension mode has a maximal value at a temperature T A (° C.),
T A (° C.) is in a range of −50 to 50° C., and
the tan δ at T A (° C.) is 2.5 or more.
2. The interlayer film according to claim 1 , wherein a tan δ obtained when a dynamic viscoelasticity of a sheet, which is obtained by molding the resin (a1) to have a thickness of 0.8 mm, is measured at a frequency of 0.3 Hz in a tension mode has a maximal value at a temperature T B (° C.), and
T B (° C.) is in a range of −100 to 100° C.
3. The interlayer film according to claim 1 , wherein a hydroxyl value of the resin (a1) is 300 mgKOH/g or less.
4. The interlayer film according to claim 1 , wherein a hydroxyl value of the resin (a1) is 20 mgKOH/g to 1000 mgKOH/g.
5. The interlayer film according to claim 1 , wherein the compound (a2) is a compound having at least one carbon atom bonded to four atoms which are all non-hydrogen atoms.
6. The interlayer film according to claim 5 , wherein the compound (a2) is a compound having a skeleton in which at least two ring structures are directly bonded to the carbon atom bonded to four atoms which are all non-hydrogen atoms.
7. The interlayer film according to claim 1 , wherein the compound (a2) is a compound having a fluorene skeleton.
8. The interlayer film according to claim 1 , wherein a hydroxyl value of the compound (a2) is 500 mgKOH/g, or less.
9. The interlayer film according to claim 1 , wherein a content of the compound (a2) is 5 to 1000 parts by mass with respect to 100 parts by mass of the resin (a1).
10. The interlayer film according to claim 1 , wherein the composition (A) comprises X parts by mass of the compound (a2) and Y parts by mass of a plasticizer (a3) different from the compound (a2) with respect to 100 parts by mass of the resin (a1), and
in a case where X parts by mass of the compound (a2) and Y parts by mass of the plasticizer (a3) are stirred at 90° C. for 8 hours and then cooled to 23° C., the entire compound (a2) is dissolved in the plasticizer (a3).
11. The interlayer film according to claim 1 , wherein a loss modulus E″ obtained when a dynamic viscoelasticity of a sheet, which is obtained by molding the composition (A) to have a thickness of 0.8 mm, is measured at a frequency of 0.3 Hz in a tension mode has a maximal value at a temperature T C (° C.),
T C (° C.) is in a range of (T A −40) to T A (° C.), and
the loss modulus E″ at T C (° C.) is 2.5×10 7 to 2.5×10 9 Pa.
12. The interlayer film according to claim 1 , wherein the sound insulating layer is disposed between two protecting layers, and
the protecting layer is formed from a composition (B).
13. The interlayer film according to claim 12 , wherein a tan δ obtained when a dynamic viscoelasticity of a sheet, which is obtained by molding the composition (B) to have a thickness of 0.8 mm, is measured at a frequency of 0.3 Hz in a tension mode has a maximal value at a temperature T D (° C.), and
T D −T A >0.
14. The interlayer film according to claim 12 , wherein the composition (B) comprises at least one resin (b1) selected from the group consisting of a polyvinyl acetal, an ethylene-vinyl acetate copolymer, and an ionomer resin.
15. The interlayer film according to claim 14 , wherein the composition (B) further comprises a plasticizer (b2), and
the resin (b1) is a polyvinyl acetal having an acetalization degree of 40 to 90 mol %.
16. A laminated glass obtained by sandwiching the interlayer film according to claim 1 between two glass plates.