Silane compositions

Details Silane compositions Silane compositions

1995-01-20

2001-04-10

Dawson, Robert (Department: 1712)

Organic compounds -- part of the class 532-570 series

Organic compounds

Silicon containing

C556S418000, C556S423000, C556S427000, C556S431000, C556S435000, C556S436000

Reexamination Certificate

active

06215011

ABSTRACT:

TECHNICAL FIELD
This invention relates to silane compositions, and more particularly, to silane compositions comprising a silane coupling agent and a tris(silylorgano)amine or alkane. The silane compositions are useful as adhesives, and more particularly, as adhesives in the preparation of multi-layer laminates such as printed circuit boards (PCBs).
BACKGROUND OF THE INVENTION
Silane compositions and silane coupling agents are well known. The use of silane coupling agents can increase the adhesive characteristics of many bonds, particularly the bond of thermosetting resins to glass, metal and metal oxide surfaces. It is well known that the bond formed by silane coupling agents is often deleteriously affected by moisture and, occasionally, the exposure of silane-coupled bonds to humid conditions can lead to the premature failure of the bond.
To minimize the effect that moisture has on silane-coupled failures, cross-linking agents have been combined with the silane coupling agents. For example, U.S. Pat. No. 4,689,085 describes silane compositions which comprise (I) a silane coupling agent; and (II) a disilyl cross-linker compound represented by the general formula
 (RO)
3
SiR′Si(OR)
3
wherein RO denotes an alkoxy group containing from 1 to 8 carbon atoms, R′ is a divalent organic group, and the weight ratio of (I) to (I) is between 1:99 and 99:1 inclusive. The silane compositions are reported to be useful as primers in the production of laminates and other composite materials.
U.S. Pat. No. 5,073,456 describes multi-layer printed circuit boards and processes for preparing multi-layer printed circuit boards utilizing a silane bonding mixture consisting essentially of (I) a ureido silane, and (II) a disilyl cross-linking agent generally represented by the formula
(RO)
3
SiR′Si(OR)
3
wherein each R is an alkyl group containing 1 to 8 carbon atoms and R′ is an alkylene group having from 1 to 8 carbon atoms.
Unfortunately, the disilyl cross-linking agents described in the '085 and '456 patents recently have been found to possess highly toxic properties as disclosed in several TSCA 8(e) submissions to the U.S. Environmental Protection Agency (for example, 8EHQ-0388-0347, 8EHQ-0392-1047, etc.). Therefore, the continued use of disilyl cross-linking agents must be closely examined and materials which can be substituted for the toxic disilyl cross-linking agents would be desirable.
SUMMARY OF THE INVENTION
Silane compositions are described which comprise (A) a silane coupling agent; and (B) a tris(silylorgano)amine or alkane characterized by the formulae
[(RO)
3
SiR
1
]
3
N  (I)
or
[(RO)
3
SiR
1
]
3
CR
2
  (II)
wherein each R is independently an alkyl, alkoxyalkyl, aryl, aralkyl or cycloalkyl group of less than 20 carbon atoms; R
1
is a divalent hydrocarbon or polyether group of less than 20 carbon atoms; and R
2
is a functional group represented by
C
n
H
2n
X
wherein n is from 0 to 20 and X is selected from the group consisting of amino, amido, hydroxy, alkoxy, halo, mercapto, carboxy, acyl, vinyl, allyl, styryl, epoxy, isocyanato, glycidoxy, and acryloxy groups. The silane compositions of the present invention are adhesive compositions providing improved bonding of surfaces such as glass, metal and metal oxides to thermosetting resins. The silane compositions also exhibit improved moisture resistance. The silane compositions are particularly useful as adhesives in preparing multi-layer laminates such as printed circuit boards.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The silane compositions of the present invention contain at least one silane coupling agent. Silane coupling agents (A) are well known, and various conventional silane coupling agents can be utilized. In one embodiment, the silane coupling agents (A) are characterized by the formula
A
(4−x)
Si(B)
x
  (III)
wherein A is a hydrolyzable group, x is 1, 2 or 3, and B is a monovalent organic group. The A groups are groups which hydrolyze in the presence of water and may include acetoxy groups, alkoxy groups containing up to 20 carbon atoms and chloro groups. In one preferred embodiment, x=1 and each A is an RO group such as represented by the formula
(RO)
3
SiB  (IIIA)
wherein each R is independently an alkyl, aryl, aralkyl or cycloalkyl group containing less than 20 carbon atoms, more often up to about 5 carbon atoms. The number of hydrolyzable groups A present in the silane coupling agent of Formula III may be 1, 2 or 3 and is preferably 3 (i.e., x=1). Specific examples of RO groups include methoxy, ethoxy, propoxy, methylmethoxy, ethylmethoxy, phenoxy, etc.
The Group B in Formula III may be an alkyl or aryl group, or a functional group represented by the formula
C
n
H
2n
X
wherein n is from 0 to 20 and X is selected from the group consisting of amino, amido, hydroxy, alkoxy, halo, mercapto, carboxy, acyl, vinyl, allyl, styryl, epoxy, isocyanato, glycidoxy and acryloxy groups. The alkyl and aryl groups may contain up to about 10 carbon atoms. Alkyl groups containing from 1 to about 5 carbon atoms are particularly useful. In one embodiment, n is an integer from 0 to 10 and more often from 1 to about 5.
The amino groups may contain one or more nitrogen atoms and, thus, may be monoamino groups, diamino groups, triamino groups, etc. General examples of diamino silane coupling agents can be represented by the formula
A
3
SiR
4
N(R
5
)R
4
N(R
5
)
2
  (IIIC)
wherein A is as defined in Formula III, each R
4
is independently a divalent hydrocarbyl group containing from 1 to about 5 carbon atoms, and each R
5
is independently hydrogen or an alkyl or an aryl group containing up to about 10 carbon atoms. The divalent hydrocarbyl groups include methylene, ethylene, propylene, etc. Each R
5
is preferably hydrogen or a methyl or ethyl group.
The silane coupling agents which may contain amido groups include compositions represented by Formula III wherein the Group B may be represented by the formulae
 —R
4
C(O)N(R
5
)
2
and
—R
4
—N(R
5
)C(O)N(R
5
)
2
wherein each R
4
is independently a divalent hydrocarbyl group containing from 1 to 20 carbon atoms, more often from 1 to about 5 carbon atoms, and each R
5
is independently hydrogen or an alkyl or aryl group containing up to about 10 carbon atoms. Thus, the amido group may be an amide group or an ureido group. Generally, each R
5
in the formulae for the amido groups is hydrogen or an alkyl group containing from 1 to about 5 carbon atoms.
In one embodiment, the silane coupling agent is a ureido silane represented by the formula
(RO)
3
SiR
4
N(H)CONH
2
  (IIIB)
wherein each R is an alkyl group containing 1 to about 5 carbon atoms, particularly methyl or ethyl groups, and R
4
is a divalent hydrocarbyl group containing from 1 to about 5 carbon atoms. Examples of such divalent hydrocarbyl groups include methylene, ethylene, propylene, butylene, etc. Specific examples of such ureido silanes include &bgr;-ureidoethyl-trimethoxysilane; &bgr;-ureidoethyl-triethoxysilane; &ggr;-ureidoethyl-trimethoxysilane; &ggr;-ureidopropyl-triethoxysilane, etc.
Other examples of silane coupling agents useful in the present invention include N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3[2(vinylbenzylamino)ethylamino]-propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, triacetoxyvinylsilane, tris-(2-methoxyethoxy)vinylsilane, 3-chloropropyltrimethoxysilane, 1-trimethoxysilyl-2-(p,m-chloromethyl)phenyl-ethane, 3-chloropropyltriethoxysilane, N-(aminoethylaminomethyl)phenyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyl tris(2-ethylhexoxy)silane, 3-aminopropyltrimethoxysilane, trimethoxysilylpropylenetriamine, &bgr;(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptotriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(2-hydroxyethyl)-3-aminopropyltrimethoxysilane, 1,3-divinyltetramethyldisilazane, vinyltrimethoxysilane, 2-(diphenylphosphino)ethyltriethoxysilane, 2-methacr

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