Biodegradable pharmaceutical compositions comprising 1,3-propanediol and its esters are provided. The 1,3-propanediol and its esters in the pharmaceutical composition are biologically derived, and as such, the pharmaceutical compositions exhibit a low anthropogenic CO.sub.2 emission profile.

A water-based ink composition is described. The water-based ink composition includes a latex containing styrene-butadiene rubber particles, and a coloring agent, the glass transition temperature of the styrene-butadiene rubber particles being 10 C. to 50 C.

A water-based ink composition is described. The water-based ink composition includes a latex containing styrene-butadiene rubber particles, and a coloring agent, the glass transition temperature of the styrene-butadiene rubber particles being 10 C. to 50 C.

There is provided a friction body which is adapted to rub a thermochromic image or handwriting formed on a paper surface by use of thermochromic ink to thermally discolor the thermochromic image or handwriting by frictional heat resultant from rubbing, a thermal conductivity of a friction portion of the friction body is set to be within 0.05 W/(m.Math.K) to 50 W/(m.Math.K).

There is provided a friction body which is adapted to rub a thermochromic image or handwriting formed on a paper surface by use of thermochromic ink to thermally discolor the thermochromic image or handwriting by frictional heat resultant from rubbing, a thermal conductivity of a friction portion of the friction body is set to be within 0.05 W/(m.Math.K) to 50 W/(m.Math.K).

A waterproof paint formula and a pen device for using the same are disclosed. The concentration of the formula may be adjusted by changing the weight percentage of the aqueous solution and cooperate with different outlet diameter of the nibs to make the waterproof paint smoothly flow out for painting on the writings. Simultaneously, the weight percentage of Ethyl Alcohol may be adjusted to control the air-dried speed of the waterproof paint to achieve the effects of waterproof and preventing the inks or colors from diffusion.

A waterproof paint formula and a pen device for using the same are disclosed. The concentration of the formula may be adjusted by changing the weight percentage of the aqueous solution and cooperate with different outlet diameter of the nibs to make the waterproof paint smoothly flow out for painting on the writings. Simultaneously, the weight percentage of Ethyl Alcohol may be adjusted to control the air-dried speed of the waterproof paint to achieve the effects of waterproof and preventing the inks or colors from diffusion.

Reversible thermochromic and photochromic ink compositions and markers, pens or writing instruments that use them are herein disclosed.

[Problem to be Solved]

An aqueous writing tool for a food product packaging material, comprising an ink with which writing can be done on food product packaging materials without being repelled can be provided.

[Solution]

An aqueous writing tool for a food product packaging material comprising an ink comprising a pigment, wherein the ink has a contact angle with a food product packaging material of 30 to 46.

[Problem to be Solved] An object of the present invention is to provide an aqueous writing tool for a food product packaging material, which can provide written products having high color developability and fixing properties upon writing on food product packaging materials.

[Solution] An aqueous writing tool for a food product packaging material comprising an ink comprising two or more pigments and one or more dispersants, wherein at least one of the pigments being a white pigment, the total content of the pigments being 10 to 25% by mass based on the total amount of the ink, and the total content of the dispersants being 1 to 5% by mass based on the total amount of the ink.