Stock material or miscellaneous articles – Circular sheet or circular blank – Recording medium or carrier
Reexamination Certificate
2000-06-28
2002-07-09
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Circular sheet or circular blank
Recording medium or carrier
C428S412000, C428S065200, C526S307700, C526S319000, C560S041000
Reexamination Certificate
active
06416838
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compositions and article made from these compositions. In preferred embodiments, the compositions do not craze polycarbonate.
BACKGROUND OF THE INVENTION
Crazing is the formation of micro cracks in on a substrate or dissolution of a portion of the substrate resulting in loss of optical clarity. Polycarbonate substrates craze under a variety of conditions including when exposed to chemicals that attack the polycarbonate substrate. Crazed polycarbonate tends to deflect and scatter light.
Polycarbonate is often used as a substrate for optical recording media such as digital versatile discs (DVDs) and digital video recordable discs (DVRs). Available DVDs often include two polycarbonate discs bonded together through an adhesive composition. One or both of the polycarbonate discs may contain data. The disc if often coated with a metal to enable the data to be read by an optical reader. Optical readers use a beam of light to read the data. In some applications, the beam of light must pass through a number of layers including, for example, a polycarbonate disc, an adhesive layer, and combinations thereof, prior to reaching the data. The nature of the layers, and in particular the refractive index of the layers, through which the beam must pass can impact the ability of the optical reader to read the data. Since optical recording medium are used for both immediate and archival purposes, it is necessary to be able to read data from an optical recording medium years after it has been stored on the DVD.
Selecting a suitable adhesive composition for use on polycarbonate substrates in general and for optical recording medium, for example, DVDs, in particular, is difficult. Adhesive compositions and components of adhesive compositions can attack polycarbonate substrates, which can cause crazing. Crazing alters the optical properties of the polycarbonate substrate and can render optical recording media unreadable, which can interfere with the short term and long term utility of an optical recording medium.
SUMMARY OF THE INVENTION
In a first aspect, the invention features compositions including polymerizable compositions and cured compositions including, for example, adhesives, that do not cause crazing in polycarbonate under certain circumstances. In one embodiment, the composition includes: a) a first monomer having the formula CH
2
═CHCOOR
1
, where R
1
is a linear alkyl group having from 9 to 16 carbon atoms or a branched alkyl group having from 9 to 30 carbon atoms, and whose homopolymer has a Tg less than 0° C.; b) a second monomer having the formula CH
2
═CHCOOR
2
, where R
2
is an alkyl group having at least 9 carbon atoms whose homopolymer has a T
g
greater than 15° C.; and c) a component comprising any of: a third monomer having the formula CH
2
═CHCONR
3
R
4
, where R
3
is hydrogen or an alkyl group having from 1 to 10 carbon atoms and R
4
is an alkyl group, when R
3
is hydrogen, R
4
is an alkyl group having from 8 to 16 carbon atoms, and when R
3
is an alkyl group having from 1 to 10 carbon atoms, R
4
is an alkyl group having a sufficient number of carbon atoms such that the sum of the carbon atoms of R
3
and R
4
is at least 8, the homopolymer of the third monomer having a T
g
greater than 15° C.; i) a monomer having the formula CH
2
CHCONHCR
5
R
6
COWP, where R
5
and R
6
are alkyl groups having from 1 to 14 carbon atoms, cycloalkyl groups having from 3 to 14 carbon atoms, aryl groups having from 5 to 12 carbon atoms, an arene group having from 6 to 16 carbon atoms and no greater than 3 atoms selected from the group consisting of S, N, and non-peroxide O, or where R
5
and R
6
when taken together with the carbon atoms to which they are connected form a carboxylic ring having 4 to 12 carbon atoms, W is O, S, NH, or a divalent connecting group, and P is ArR
7
, where Ar is an arylene group and R
7
is a linear or branched alkyl or alkoxy group, an aryl group, or an alkarylene group such that the total number of carbon atoms in ArR
7
is at least 10, or
where x is from 1 to 4, and R
8
is linear or branched alkyl group having at least 4 carbon atoms; ii) a monomer having the formula
where R
9
is H or CH
3
, x is from 1 to 4, and R
10
is a linear or branched alkyl group having at least 4 carbon atoms; iii) a monomer having the formula CH
2
═CHCOO(R
11
)
n
OCOCH═CH
2
, where R
11
is a linear or branched alkylene and n is at least 6; iv) a polymer having a molecular weight greater than about 1500 and being soluble in at least one of the first monomer and the second monomer; v) surface-modified particles; and vi) combinations thereof, wherein the composition does not cause crazing in polycarbonate when in contact with polycarbonate for a period of about 30 minutes at 25° C.
In a second aspect, the invention features a composition that includes at least one polymerizable component and crystalline zirconia particles having an average primary particle size no greater than about 20 nm and having a dispersion index of from about 1-3, where the particles have a crystallinity index of at least about 0.65 and at least about 70% combined cubic and tetragonal crystal lattice structure in the absence of a cubic tetragonal crystal phase stabilizer. In one embodiment, the composition is coated on a substrate to modify the refractive index of the substrate.
In a third aspect, the invention features a composition that includes the reaction product of a reaction mixture that includes an above-described composition a crosslinking agent, and a photoinitiator. In one embodiment, the composition is an adhesive (for example, a pressure sensitive adhesive).
In a fourth aspect, the invention features an article that includes polycarbonate substrate and an above-described composition on the substrate. In one embodiment, the article further includes a second polycarbonate substrate, and the composition is disposed between the first polycarbonate substrate and the second polycarbonate substrate. In some embodiments, the article is an optical recording medium, for example, a DVD or DVR.
In a fifth aspect, the invention features compounds having the formula CH
2
═CHCONHC(CH
3
)
2
COOCH
2
CH
2
—R, where R is OC
6
H
5
, S—C
6
H
5
, S—CH
2
CH
3
, O—C
6
H
4
—C(CH
3
)
3
, or O—C
6
H
4
—C(CH
3
)
2
—C
6
H
5
.
In a sixth aspect, the invention features adhesive compositions that include the reaction product of a reaction mixture that includes a compound comprising compounds having the formula: CH
2
═CHCONHC(CH
3
)
2
COOCH
2
CH
2
—R, where R is OC
6
H
5
, S—C
6
H
5
, S—CH
2
CH
3
, O—C
6
H
4
—C(CH
3
)
3
, or O—C
6
H
4
—C(CH
3
)
2
—C
6
H
5
.
The compositions of the present invention preferably do not craze polycarbonate substrates under certain circumstances. The compositions of the present invention enhance the archival function and potential for optical discs that include these compositions since these compositions can be formulated to be free of crazing for extended periods. For example, the compositions enable the manufacture of optical recording medium, for example, DVDs and DVRs, that are resistant to crazing.
In addition, a variety of components can be added to the composition to achieve a composition that is does not cause crazing in polycarbonate and to alter properties of the composition including, for example, refractive index, viscosity, cleavage strength to polycarbonate, and combinations thereof.
The inclusive of colloidal particles, for example, can increase the refractive index of the composition. This is particularly useful in optical disc applications, such as DVD, that require digital data to be read through the composition.
The invention provides an adhesive composition that exhibits good bond strength to polycarbonate substrates such that it maintains the bond under conditions of elevated temperature (at about 70° C.). The adhesive composition also provides a bond to polycarbonate of good durability. The bond integrity is also maintained when cooled to room temperature after exposure to elevated
Arney David S.
Bennett Richard E.
Gaddam Babu N.
Heilmann Steven M.
Kolb Brant U.
3M Innovative Properties Company
Dawson Robert
Feely Michael J
Pastirik Daniel R.
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