what is claimed is:
1. A cathode ray tube, comprising:
a panel including a front screen portion and a panel flange formed on an edge of said front screen portion, a phosphor screen being formed on said screen portion;
a funnel connected to said panel flange;
a deflection yoke disposed around the funnel;
a neck connected to said funnel;
an electron gun disposed in said neck;
a color selection apparatus selecting electron beams emitted from said electron gun and allowing the selected electron beams to land on corresponding phosphors, said color selection apparatus comprising a frame including a pair of supporting members disposed at a predetermined distance from each other in parallel and a pair of elastic members secured on both ends of said supporting members to correspond to lateral sides of a mask; and
a shield apparatus for shielding geomagnetism, said shield apparatus mounted on a perimeter of said frame of said color selection apparatus and extended toward said neck, said shield apparatus includes disconnection parts defined corresponding to corners of said frame, said shield apparatus being extended toward the phosphor screen over one of longitudinal and lateral sidewalls of said frame.
2. The cathode ray tube of claim 1, said shield apparatus further comprising a main shield member including a body provided with an electron beam-passing opening and extended toward said neck, and a skirt extended from said body and disposed on longitudinal sides of said frame; and
a sub-shielding member disposed on lateral sides of said frame.
3. The cathode ray tube of claim 2, said skirt being secured on said supporting members while covering a center of said supporting members.
4. The cathode ray tube of claim 3, said skirt being formed to be asymmetrical with reference to a central portion of said supporting members.
5. The cathode ray tube of claim 2, said main shield member being mounted on said frame while not enclosing said elastic members.
6. The cathode ray tube of claim 2, said sub-shield member further comprising:
a shielding part disposed along the lateral sides of said frame to cover a space defined between said mask and said elastic members; and
bridges extended from said shielding part and secured on said elastic members.
7. The color selection apparatus of claim 6, further comprised of a width of said shielding part being greater than a width of said frame.
8. The cathode ray tube of claim 2, said sub-shield member further comprising:
a shielding part disposed along the lateral sides of said frame to cover a space defined between said mask and said elastic members; and
a securing part bent at both ends of said shielding part and securing on said supporting members.
9. The cathode ray tube of claim 2, said skirt being connected to said supporting members while satisfying the following condition:
0.01 mmtkL0.15 mm
where t is a thickness of said sub-shield member, k is a length of said skirt extending from said mask toward said phosphor screen, and L is a height of said supporting member.
10. The cathode ray tube of claim 9, said skirt being connected to said supporting members while satisfying the following condition:
0.04 mmtkL0.12 mm.
11. The cathode ray tube of claim 9, said sub-shield member being secured on said supporting member under the following condition:
0.01 mmtkL0.15 mm
where t is a thickness of said sub-shield member, k is a length of said sub-shield member extending from said mask toward said phosphor screen, and L is a height of said supporting member.
12. The cathode ray tube of claim 11, said sub-shield member being secured on said supporting member under the following condition:
0.04 mmtkL0.12 mm.
13. A cathode ray tube, comprising:
a color selection apparatus selecting electron beams emitted from an electron gun and allowing the selected electron beams to land on corresponding phosphors, said color selection apparatus comprising a frame including a pair of supporting members disposed at a predetermined distance from each other in parallel and a pair of elastic members secured on both ends of said supporting members to correspond to lateral sides of a mask; and
a shield apparatus shielding from geomagnetism and being mounted on a perimeter of said frame of said color selection apparatus and extended toward a neck of said cathode ray tube, said shield apparatus being extended toward a phosphor screen over one of longitudinal and lateral sidewalls of said frame, said shield apparatus, comprising:
a main shield member including a skirt disposed on the longitudinal sides of said frame; and
a sub-shield member disposed on the lateral sides of said frame, said sub-shield member covering a space defined between said mask and said elastic members.
14. The cathode ray tube of claim 13, further comprising a disconnection part defined by said skirt and said sub-shield member being disconnected from each other.
15. The cathode ray tube of claim 14, said disconnection part being at the corners of said frame.
16. The cathode ray tube of claim 13, said sub-shielding member further comprising:
a shielding part being arranged in a longitudinal direction to cover the space between said mask and said elastic member; and
a bridge integrally extending from said shielding part and being secured to said elastic members.
17. The cathode ray tube of claim 13, said sub-shielding member further comprising:
a shielding part covering a space between the lateral sides of said frame and said elastic member; and
a securing part being bent at both ends of said shielding part and secured on said supporting member.
18. The cathode ray tube of claim 13, said skirt covering a central portion of said supporting member and being asymmetrical with reference to the central portion of said supporting member, said skirt being connected to said supporting members while satisfying a condition based on a thickness of said skirt, a length of said skirt extending from said mask toward said phosphor screen, s and a height of said supporting member.
19. The cathode ray tube of claim 13, said sub-shield member being connected to said support members while satisfying a condition based on a thickness of said sub-shield member, a length of said sub-shield member extending from said mask toward said phosphor screen, and the height of said supporting members.
20. A cathode ray tube, comprising:
a color selection apparatus selecting electron beams emitted from an electron gun and allowing the selected electron beams to land on corresponding phosphors, said color selection apparatus comprising a frame including a pair of supporting members disposed at a predetermined distance from each other in parallel and a pair of elastic members secured on both ends of said supporting members to correspond to lateral sides of a mask; and
a shield apparatus shielding from geomagnetism and being mounted on a perimeter of said frame of said color selection apparatus and extended toward a neck of said cathode ray tube, said shield apparatus being extended toward a phosphor screen over one of longitudinal and lateral sidewalls of said frame, said shield apparatus, comprising:
a main shield member including a skirt disposed on longitudinal sides of said frame, said skirt being secured to said supporting members, covering a central portion of said supporting member and being asymmetrical with reference to the central portion of said supporting member;
a sub-shield member disposed on lateral sides of said frame, said sub-shield member covering a space defined between said mask and said elastic members, a width of said sub-shielding member being greater than a width of the lateral sides of said frame; and
a disconnection part defined by said skirt and said sub-shield member being disconnected from each other at the corners of said frame.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A process for preparing N,N-dimethylacetamide (DMAC) comprising the step of continuously reacting methyl acetate (MeOAc) with dimethylamine (DMA) in the presence of a basic catalyst, wherein said MeOAc is in the form of a methanolic solution obtained as a by-product in the preparation of polyTHF via transesterification of polyTHF diacetate with methanol.
2. The process according to claim 1, wherein said reaction is carried out at a temperature in the range from 80 to 140\xb0 C.
3. The process according to claim 1, wherein said reaction is carried out at an absolute pressure in the range from 3 to 30 bar.
4. The process according to claim 1, wherein said methanolic MeOAc solution comprises from 70 to 85% by weight of MeOAc, from 14.8 to 25% by weight of methanol, from 0.1 to 1.5% by weight of dimethyl ether, from 0.1 to 3.5% by weight of tetrahydrofuran (THF), and from 0 to 0.01% by weight of water.
5. The process according to claim 1, wherein said methanolic MeOAc solution comprises from 75 to 82% by weight of MeOAc, from 17.6 to 22% by weight of methanol, from 0.2 to 1.2% by weight of dimethyl ether, from 0.2 to 1.5% by weight of THF, and from 0 to 0.003% by weight of water.
6. The process according to claim 1, wherein said catalyst is sodium methoxide.
7. The process according to claim 6, wherein said catalyst is in the form of a methanolic solution.
8. The process according to claim 1, wherein said catalyst is present in the range of from 0.0002 to 0.09 mole per mole of MeOAc.
9. The process according to claim 1, wherein said reaction is carried out in a jet loop reactor.
10. The process according to claim 9, wherein said jet loop reactor comprises an insert tube and a nozzle located at the bottom of said jet loop reactor.
11. The process according to claim 1, comprising the additional step of neutralizing said catalyst present in the reactor effluent after the reaction and before distillative workup by reacting said catalyst with a protic acid or by decomposing said catalyst with water.
12. The process according to claim 11, wherein said protic acid is phosphoric acid.
13. The process according to claim 11, comprising the additional step of removing the organic product mixture after neutralization with a protic acid and before distillative workup by evaporating said organic product mixture from salts present after the reaction.
14. The process according to claim 1, comprising the additional step of continuously distillatively working-up reaction effluent in a column A, wherein methanol and any other low boilers are initially removed overhead in column A, followed by feeding the bottom effluent of column A to a column B, wherein DMAC is removed via a side draw, and wherein said DMAC has a purity of greater than or equal to 99.7% by weight.
15. The process according to claim 14, wherein said DMAC is removed in column B via a liquid side draw which is disposed in the rectifying section of column B.
16. The process according to claim 14, wherein the top effluent of column B comprises DMAC and is recycled back into column A.
17. The process according claim 14, wherein the bottom effluent of column B is separated into a column C, wherein the top effluent of column B is recycled into column A, and wherein said top effluent comprises DMAC and methanol.
18. The process according to claim 14, wherein the top effluent of column A comprises methanol and is purified in a column D.
19. The process according to claim 1, wherein the DMAC prepared has a purity of greater than or equal to 99.7% by weight, a water content of less than or equal to 200 ppm, and a PtCo color number less than or equal to 10.
20. The process according to claim 1, wherein the DMAC prepared has an acid content calculated as acetic acid of less than or equal to 80 ppm.
21. The process according to claim 1, wherein said process is carried out in a plant wherein DMF can also be prepared from carbon monoxide and DMA.