Acrylic compositions including a hindered amine light stabilizer and methods of making and using the same

An acrylic fiber comprising:

• an acrylonitrile polymer having acrylonitrile units present in an amount of at least 85% by weight of the acrylonitrile polymer;
• and
• a hindered amine light stabilizer;
• wherein the hindered amine light stabilizer has a pKa from 4 to 7 and has a water solubility at 20° C. of about 2% w/w or less;
• wherein the hindered amine light stabilizer is within the acrylic fiber in an amount of about 0.5% to about 10% by weight of the acrylic fiber and is distributed throughout the polymer matrix of the acrylonitrile polymer;
• wherein the acrylonitrile polymer is selected from the group consisting of polyacrylonitrile (PAN), poly(acrylonitrile-co-vinyl acetate) (P(AN-VA)), poly(acrylonitrile-co-methyl acrylate) (P(AN-MA)), poly(acrylonitrile-co-vinyl chloride) (PAN-VC), poly(acrylonitrile-co-vinylidene chloride, poly(acrylonitrile-co-methyl methacrylate), and any combination thereof;
• and
• wherein the hindered amine light stabilizer has a structure represented by Formula (I), Formula (II), Formula (III), or Formula (IV):
• wherein:
• each X is independently selected from the group consisting of C1-C20 alkyl and C1-C20 alkenyl;
• L, in each instance, is absent or is independently selected from the group consisting of C1-C20 alkyl and C1-C20 alkenyl;
• each R1 is independently selected from the group consisting of C1-C20 alkyl, C1-C20 alkenyl, —O(C1-C20 alkyl), and —O(C1-C20 alkenyl);
• each R2 is independently selected from the group consisting of hydrogen, C1-C20 alkyl, and C1-C20 alkenyl;
• each R3 is independently selected from the group consisting of hydrogen, C1-C20 alkyl, and C1-C20 alkenyl;
• and
• n is an integer selected from 1 to 50.

An acrylic composition comprising:

• an acrylonitrile polymer having acrylonitrile units present in an amount of at least 85% by weight of the acrylonitrile polymer;
• and
• a hindered amine light stabilizer in an amount of about 0.5% to about 10% by weight of the acrylic composition;
• wherein the acrylonitrile polymer comprises one or more comonomer units selected from the group consisting of vinyl acetate, styrene, methyl methacrylate, vinyl acetate, methyl acrylate, sodium styrene sulfonate, sodium methallyl sulfonate, sodium sulfophenyl methallyl, ether, itaconic acid, and any combination thereof;
• wherein the hindered amine light stabilizer has a pKa from 4 to 7;
• wherein the acrylic composition, when formed into an acrylic fiber devoid of a pigment, has a Gray scale value of 5 after exposure to about 100 kJ of light;
• and
• wherein the hindered amine light stabilizer has a structure represented by Formula (I), Formula (II), Formula (III), or Formula (IV):
• wherein:
• each X is independently selected from the group consisting of C1-C20 alkyl and C1-C20 alkenyl;
• L, in each instance, is absent or is independently selected from the group consisting of C1-C20 alkyl and C1-C20 alkenyl;
• each R1 is independently selected from the group consisting of C1-C20 alkyl, C1-C20 alkenyl, —O(C1-C20 alkyl), and —O(C1-C20 alkenyl);
• each R2 is independently selected from the group consisting of hydrogen, C1-C20 alkyl, and C1-C20 alkenyl;
• each R3 is independently selected from the group consisting of hydrogen, C1-C20 alkyl, and C1-C20 alkenyl;
• and
• n is an integer selected from 1 to 50.

An acrylic fiber comprising:

• an acrylonitrile polymer having acrylonitrile units present in an amount of at least 85% by weight of the acrylonitrile polymer;
• and
• a hindered amine light stabilizer in an amount of about 0.5% to about 10% by weight of the acrylic fiber;
• wherein the hindered amine light stabilizer has a pKa from 4 to 7;
• wherein the acrylonitrile polymer is selected from the group consisting of polyacrylonitrile (PAN), poly(acrylonitrile-co-vinyl acetate) (P(AN-VA)), poly(acrylonitrile-co-methyl acrylate) (P(AN-MA)), poly(acrylonitrile-co-vinyl chloride) (PAN-VC), poly(acrylonitrile-co-vinylidene chloride, poly(acrylonitrile-co-methyl methacrylate), and any combination thereof;
• wherein the hindered amine light stabilizer is within the acrylic fiber and is distributed throughout a cross-section of the acrylic fiber;
• and
• wherein the hindered amine light stabilizer has a structure represented by Formula (I), Formula (II), Formula (III), or Formula (IV):
• wherein:
• each X is independently selected from the group consisting of C1-C20 alkyl and C1-C20 alkenyl;
• L, in each instance, is absent or is independently selected from the group consisting of C1-C20 alkyl and C1-C20 alkenyl;
• each R1 is independently selected from the group consisting of C1-C20 alkyl, C1-C20 alkenyl, —O(C1-C20 alkyl), and —O(C1-C20 alkenyl);
• each R2 is independently selected from the group consisting of hydrogen, C1-C20 alkyl, and C1-C20 alkenyl;
• each R3 is independently selected from the group consisting of hydrogen, C1-C20 alkyl, and C1-C20 alkenyl;
• and
• n is an integer selected from 1 to 50.