Heat reservoir comprising porous substrate impregnated with latent heat storage material and method for producing the same

1. A heat reservoir, comprising:

a porous substrate being a wooden molded article formed from wooden fibers or wooden pieces; and

a heat storage material composition;

wherein:

the porous substrate is impregnated with the heat storage material composition;

the heat storage material composition comprises a latent heat storage material and a hydrogenated styrene-based thermoplastic elastomer;

the porous substrate has a surface having a plurality of holes formed thereon;

each of the holes has an opening at the surface of the porous substrate;

a greatest dimension of each of the openings is 2 to 20 mm;

each of the openings has an area of 2 mm 2 or greater;

each of the holes is a bottomed hole that extends in a direction perpendicular to the surface or a through-hole that extends in a direction perpendicular to the surface and completely penetrates the porous substrate; and

a weight-average molecular weight of the hydrogenated styrene-based thermoplastic elastomer and an amount of the hydrogenated styrene-based thermoplastic elastomer are related such that, when the weight-average molecular weight of the hydrogenated styrene-based thermoplastic elastomer is given by X×10 4 and the amount of the hydrogenated styrene-based thermoplastic elastomer is given by Y parts by mass relative to 100 parts by mass of the latent heat storage material in the heat storage material composition, X and Y are defined as follows:

5≤X≤17;

5≤Y≤25;

when 5≤X<10, −2X+25≤Y≤25; and

when 14<X≤17, 5≤Y≤−5X+90.

2. The heat reservoir according to claim 1 , wherein the heat storage material composition has viscosity of 500 mPa·s or less at 100° C. when measured with a B-type viscometer.

3. The heat reservoir according to claim 1 , wherein 7.5≤X≤15.

4. The heat reservoir according to claim 2 , wherein 7.5≤X≤15.

5. The heat reservoir according to claim 1 , wherein X and Y are defined as follows:

when 5≤X<10, −2X+30≤Y≤−X+30;

when 10≤X<14, −(5/7)X+(120/7)≤Y≤−1.25X+32.5; and

when 14≤X≤17, −(5/7)X+(120/7)≤Y≤−(10/3)X+(185/3).

6. The heat reservoir according to claim 2 , wherein X and Y are defined as follows:

when 5≤X<10, −2X+30≤Y≤−X+30;

when 10≤X<14, −(5/7)X+(120/7)≤Y≤−1.25X+32.5; and

when 14≤X≤17, −(5/7)X+(120/7)≤Y≤−(10/3)X+(185/3).

7. The heat reservoir according to claim 3 , wherein X and Y are defined as follows:

when 5≤X<10, −2X+30≤Y≤−X+30;

when 10≤X<14, −(5/7)X+(120/7)≤Y≤−1.25X+32.5; and

when 14≤X≤17, −(5/7)X+(120/7)≤Y≤−(10/3)X+(185/3).

8. A method for producing the heat reservoir according to claim 1 , comprising:

melting the heat storage material composition; and

impregnating the porous substrate with the molten heat storage material composition.

9. The method according to claim 8 , wherein the heat storage material composition has a viscosity of 500 mPa·s or less at 100° C. when measured with a B-type viscometer.

10. The method according to claim 8 , wherein 7.5≤X≤15.

11. The method according to claim 9 , wherein 7.5≤X≤15.

12. The method according to claim 8 , wherein X and Y are defined as follows:

when 5≤X<10, −2X+30≤Y≤−X+30;

when 10≤X<14, −(5/7)X+(120/7)≤Y≤−1.25X+32.5; and

when 14≤X≤17, −(5/7)X+(120/7)≤Y≤−(10/3)X+(185/3).

13. The method according to claim 9 , wherein X and Y are defined as follows:

when 5≤X<10, −2X+30≤Y≤−X+30;

when 10≤X<14, −(5/7)X+(120/7)≤Y≤−1.25X+32.5; and

when 14≤X≤17, −(5/7)X+(120/7)≤Y≤−(10/3)X+(185/3).

14. The method according to claim 10 , wherein X and Y are defined as follows:

when 5≤X<10, −2X+30≤Y≤−X+30;

when 10≤X<14, −(5/7)X+(120/7)≤Y≤−1.25X+32.5; and

when 14≤X≤17, −(5/7)X+(120/7)≤Y≤−(10/3)X+(185/3).