Bonding sheet material for weather strip, weather strip, and method for producing same

A bonding sheet material for a weather strip, the bonding sheet material being configured to bond opposite end portions of a weather strip material to each other, wherein

• the bonding sheet material is a composition including at least EPDM, a cross-linking agent, and carbon black,
• the bonding sheet material has a volume resistivity of 1.0 × 106 Ω·cm or more based on a double ring electrode method of JIS-K6271-1:
• 2015 where a test piece has a thickness of 2 mm,
• when the composition is placed in a mold and molded to press the composition at 50° C. under 100 Kgf/cm2 for 60 seconds whereby a molded article is produced, the molded article has a thickness change rate of 100% or less, the thickness change rate being represented by a formula (1), and
• the formula (1):
• Thickness change rate
• =
• thickness of molded article after 30
• minutes from releasing press -
• thickness of mold
• /
• thickness of mold
• ×
• 100
• .

A weather strip comprising:

• a main body portion having end portions;
• and
• a bonding portion that bonds the opposite end portions of the main body portion to each other, wherein
• the bonding portion is formed of a cross-linked product of a bonding sheet material, and
• the bonding sheet material satisfies all of the following conditions:
• a composition including at least EPDM, a cross-linking agent, and carbon black;
• when a total amount of the composition configuring the bonding sheet material is defined as 100% by volume, a blending ratio of the carbon black is 11% or more by volume and 19% or less by volume;
• and
• a volume resistivity is 1.0 × 106 Ω·cm or more based on a double ring electrode method of JIS-K6271-1:
• 2015 where a test piece has a thickness of 2 mm.

A method for producing a weather strip including a main body portion having end portions and a bonding portion that bonds the opposite end portions of the main body portion to each other, the method comprising:

• preparing a weather strip material for forming the main body portion and a bonding sheet material for forming the bonding portion;
• and
• cross-linking the bonding sheet material by placing the bonding sheet material between the opposite end portions of the weather strip material, wherein
• the bonding sheet material satisfies all of the following conditions:
• a composition including at least EPDM, a cross-linking agent, and carbon black;
• a volume resistivity of 1.0 × 106 Ω·cm or more based on a double ring electrode method of JIS-K6271-1:
• 2015 where a test piece has a thickness of 2 mm;
• when the composition is placed in a mold and molded to press the composition at 50° C. under 100 Kgf/cm2 for 60 seconds whereby a molded article is produced, the molded article has a thickness change rate of 100% or less, the thickness change rate being represented by a formula (1);
• and
• the formula (1):
• Thickness change rate
• =
• thickness of molded article after 30
• minutes from releasing press -
• thickness of mold
• /
• thickness of mold
• ×
• 100
• .