Hot melt adhesive

1. A hot melt adhesive comprising a thermoplastic polymer and a tackifier, wherein

the tackifier includes an acid-modified tackifier that is modified by at least one of maleic acid and maleic anhydride, and by butyl methacrylate,

the acid-modified tackifier is a random or block copolymer having repeating units represented by Formula 1 below

in Formula 1, R 1 and R 2 are independently a hydrogen atom or functional unit represented by Formula 2 below, a is 0 to 3, at least one among a plurality of R 1 and R 2 is the functional unit represented by Formula 2 below, the ratio of n in the total of n and m is from 0 or more to less than 1,

the functional unit represented by Formula 2 is a random or block copolymer having a repeating unit represented by Formula 2, R 3 in Formula 2 is butyl group, R 4 in Formula 2 is methyl group, and each of l and k is 1 or more.

2. The hot melt adhesive according to claim 1 , wherein the thermoplastic polymer is a copolymer of a conjugated diene compound and a vinyl aromatic hydrocarbon.

3. The hot melt adhesive according to claim 2 , wherein the copolymer is at least one selected from the group consisting of a styrene-butadiene block copolymer, a styrene-isoprene block copolymer, a hydrogenated styrene-butadiene block copolymer, and a hydrogenated styrene-isoprene block copolymer.

4. The hot melt adhesive according to claim 1 , wherein an amount of the acid-modified tackifier is 0.1 mass % to 100 mass % based on a total amount of the tackifier.

5. The hot melt adhesive according to claim 1 , wherein

an amount of the thermoplastic polymer is 10 mass % to 75 mass %; and

an amount of the tackifier is 20 mass % to 80 mass %.

6. The hot melt adhesive according to claim 1 , further comprising a softener.

7. The hot melt adhesive according to claim 6 , wherein an amount of the softener is 5 mass % to 40 mass %.