JPH0811783B2 - Organopolysiloxane coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a translucent, high strength organopolysiloxane liquid injection molding composition. More particularly, the present invention relates to such compositions that cure by SiH addition reaction with a controlled mixture of olefin-containing organopolysiloxanes.

BACKGROUND OF THE INVENTION Liquid injection moldable (LIM) organopolysiloxane compositions are known and used. The problem common to all such compositions is that they impair other properties because the coating speed, altitude, tensile strength, elongation and tear are interdependent with each other and with the viscosity of the uncured liquid. It is difficult to improve some properties without. In particular, it is desirable to improve hardness and tear strength without degrading other properties.

Jeram U.S. Pat. No. 3,884,866 and
No. 3,957,713 describes a high strength addition curable composition suitable for low pressure liquid injection molding. These compositions include a high viscosity, vinyl-terminated organopolysiloxane, a low viscosity, vinyl-containing organopolysiloxane, a filler, and a first component containing a platinum catalyst, This first component is cured by mixing it with a second component containing a hydrogen silicone composition. This composition is difficult to apply, ie the application rate is slow, and further attempts to increase the application rate by reducing the viscosity of the components adversely affect other properties.

Lee et al., U.S. Pat. No. 4,162,243, discloses a fumed silica similar to the composition of Jeram, but with the most important difference being treated with hexamethyldisilazane and tetramethyldivinyldisilazane. Compositions containing are disclosed. The composition of Lee et al. Is an elastomer that has a low viscosity in the uncured state, yet has a high hardness when cured, yet retains other properties such as strength, elongation and tear. become.

In US Pat. No. 4,427,801 to Sweet,
In addition to treated fumed silica containing vinyl
By adding MM ^Vi Q resin, the composition of Lee et al. Is improved and expanded. According to this, an elastomer having higher hardness and tear strength is produced, but it has a drawback that the compression strain is high and the Bashore impact resilience is low.

It is an object of the present invention to produce an organopolysiloxane composition for liquid injection molding which has improved and facilitated application without adversely affecting other physical properties.

It is another object of the present invention to produce a composition with such a liquid injection molding organopolysiloxane composition having a particular coating speed.

These and other objects will be apparent to those of ordinary skill in the art in view of the detailed description, examples and claims set forth herein.

Detailed Description of the Invention According to the present invention, low viscosity, high viscosity, good elongation,
LIM organopolysiloxane compositions are provided that combine good hardness and tear strength with exceptionally high application rates. This composition consists of the following (A) to (D).

(A) 100 parts by weight of a vinyl-containing polyorganosiloxane component consisting of the following (1) and (2): (1) Having 25 mol% or less of phenyl groups, and at 25 ° C.
60-75 parts by weight of linear, high-viscosity, vinyl-terminated organopolysiloxane having a viscosity of 5,000-40,000 centipoise, and (2) having at least one terminal vinyl group per molecule, Vinyl having a vinyl content that can vary from 0.01 mol% to 60 mol% vinyl, a viscosity at 25 ° C that varies from about 50 to about 2,000 centipoise, and having 25 mol% or less phenyl groups, linear. 25-40 parts by weight of low viscosity organopolysiloxane.

(B) About 5 to about 70 parts by weight of one kind of filler or a combination of two or more kinds of fillers.

(C) The platinum catalyst is about 0.1 to 50 ppm of the total organopolysiloxane composition.

(D) selected from the group consisting of hydrogen-containing silanes and hydrogen-containing organopolysiloxanes
About 0.5 to 25 parts by weight of SiH composition.

The composition can be cured at room temperature for 16 hours to give an elastomer, or it can be cured at elevated temperatures such as 200 ° C. for 10 seconds. In a preferred embodiment, the composition is a two-component composition, the first component containing at least all of component (C) and the second component containing at least all of component (D). .

The linear, high-viscosity vinyl-terminated organopolysiloxane A (1) of the present invention has a maximum of 25 mol% phenyl groups and a viscosity at 25 ° C. of from about 5,000 to about 40,000 centipoise, Preferred is about 10,000 to about 25,000 centipoise at 25 ° C. These high viscosity organopolysiloxanes can be represented by the general formula:

Where Vi represents vinyl, R is selected from the group consisting of monovalent hydrocarbon groups having up to about 20 carbon atoms and halogenated monovalent hydrocarbon groups, and x is about 100
To about 10,000, with 500 to 2,000 being preferred.

Linear low viscosity organopolysiloxane A of the present invention
(2) has at least one terminal vinyl group per molecule and has a vinyl content of about 0.01 mol% vinyl to about 60 vinyl.
It can vary up to mol%, preferably 0.05 to 10 mol% vinyl. The viscosity varies from about 50 to about 2,000 centipoise at 25 ° C, preferably from about 50 to about 1,000 centipoise at 25 ° C. Further, A (2) has about 25 mol% or less of phenyl groups. These low viscosity organopolysiloxanes can be represented by the general formula:

Where R is as defined above, R ¹ is the same as R, but at least one of R ¹ must be vinyl and y can vary from about 1 to about 300. it can.
Suitable low viscosity organopolysiloxanes are disclosed in U.S. Pat.
No. 884,866, the disclosures of which are hereby incorporated by reference.

As mentioned above, R is a monovalent hydrocarbon radical having up to about 20 carbon atoms and a halogenated monovalent hydrocarbon radical, ie a radical usually attached as a substituent of an organopolysiloxane. Is selected from the group consisting of:
Thus, the group R is a mononuclear and binuclear aryl group such as phenyl, tolyl, xylyl, naphthyl, etc .; a halogenated mononuclear and binuclear aryl group such as chlorophenyl, chloronaphthyl, etc .; benzyl, phenyl, etc. Mononuclear aryl-lower alkyl groups (1-8 carbon atoms in each alkyl group); lower alkyl having 1-8 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl and the like. Groups; lower alkenyl groups of 2 to 8 carbon atoms such as vinyl, allyl, 1-propenyl, etc .; halo lower alkyl groups of 1 to 8 carbon atoms such as chloropropyl, trifluoropropyl, etc .; and cyclobutyl, cyclopentyl , Cyclohexyl and the like, can be selected from the group consisting of cycloalkyl groups.
Those skilled in the art will appreciate that R may be any of those listed above, but not all R may be high molecular weight groups and that R should be selected so as not to adversely affect the reaction of the vinyl group. Will be easily recognized. R is preferably a lower alkyl group having 1 to 8 carbon atoms such as methyl, ethyl and phenyltrifluoropropyl. More preferably, at least about 70% (by number) of R is methyl.

The essence of the present invention, in particular the distinction between prior art SiH / olefin-added silicone rubber compositions and the present invention, is that the low viscosity vinyl-containing organopolysiloxane and the high viscosity vinyl-containing organopolysiloxane are in a critical ratio. Is present in the composition. Within this ratio range, compositions with high coating speeds can be produced without adversely affecting other physical properties. As already mentioned, these vinyl-containing organopolysiloxanes are high-viscosity organopolysiloxane A (1) and low-viscosity organopolysiloxane A (2). For every 100 parts by weight of vinyl-containing organopolysiloxane, 60 to 75 parts by weight of A (1),
A (2) should be 25-40 parts by weight. This vinyl-containing organopolysiloxane mixture results in a cured composition with good hardness, high tear, high tensile strength and good elongation with an exceptionally high coating speed.
The cured composition exhibits a coating rate of at least 100 g / min and a tensile strength of about 900 psi or more, an elongation of about 500% or more, a tear strength of about 175 psi or more, and a shore (30-35 or more). Shore) A hardness.

The SiH composition (D) of the present invention acts as a crosslinking agent and can be selected from the group consisting of hydrogen-containing silanes and hydrogen-containing organopolysiloxanes. Organopolysiloxanes containing hydrogen are preferred. The hydrogen-containing organopolysiloxane of the present invention can be characterized as a copolymer containing at least one unit having the formula (3) per molecule.

_{(3) R f H g SiO} (4-f-g) / 2 remaining siloxane units in the organopolysiloxane has the formula (4).

(4) R _c SiO _{(4-C) / 2} where R in the above formula is as previously defined but must be saturated, c has a value from 0 to 3 and f
Has a value from 0 to 2 and the sum of f and g is equal to 1.0 to 3.0. The viscosity of the hydrogen-containing organopolysiloxane should range from about 5 to about 1,000 centipoise at 25 ° C, with about 5 to about 100 centipoise being preferred. The copolymer usually contains 0.5 to 99.5 mol% of units of formula (3) and 0.5 to 99.5 mol% of units of formula (4).

Among the above hydrogen-containing organopolysiloxanes, preferred are MQ resins having, for example, H (R) ₂ SiO _1/2 units and SiO ₂ units. Similarly, MDQ, M with hydrogen substitution
Resins such as TQ and MDT are also included. The copolymer usually contains 0.5 to 99.5 mol% of units of formula (6) and 0.5 to 99.5 mol% of units of formula (4).

Another suitable hydrogen containing organopolysiloxane is the MQ resin organopolysiloxane of the formula:

Where R is as previously defined (excluding unsaturated compounds), R ³ is the same as R, but with the exception of unsaturated compounds and including hydrogenation, h varies from 1 to 200 , I varies from 5 to 200. It is preferable that h varies from 10 to 100 and i varies from 5 to 100.

The organopolysiloxane (D) containing hydrogen is
It is used at a concentration of about 0.5 to 25 parts by weight per 100 parts by weight of (A), but is preferably used at a concentration of about 0.5 to 10 parts by weight per 100 parts by weight of (A). In this SiH material,
It is preferred that there be at least one hydrogen atom for each vinyl group in (A) and from about 1.5 to about 2.5 hydrogen atoms for each vinyl group.

Various types of platinum catalysts for this SiH olefin addition reaction are known, and such platinum catalysts can also be used in the reaction of the present invention. A platinum catalyst which is particularly preferable when optical transparency is required is a platinum compound catalyst soluble in the reaction medium of the present invention. The platinum compound may be selected from those having the formula (PtCl ₂ olefin) ₂ and H (PtCl ₃ olefin) as described in Ashby US Pat. No. 3,159,601. The olefins shown in these formulas can be almost any type of olefin, but with 2 to 2 carbon atoms.
Preference is given to alkylene having 8 and cycloalkylene having 5 to 7 carbon atoms or styrene. Specific olefins that can be used in the above formula are ethylene, propylene, various isomers of butylene, octylene,
Examples include cyclopentene, cyclohexene and cycloheptene.

Yet another platinum-containing material that can be used in the compositions of the present invention is the platinum chloride cyclopropane complex (PtCl ₂ C ₃ H ₆ ) described in Ashby US Pat. No. 3,159,662.
₂ .

In addition, this platinum-containing material is
x) selected from the group consisting of chloroplatinic acid as described in U.S. Pat. No. 3,220,972 and up to 2 moles of alcohols, ethers, aldehydes and mixtures thereof per gram of platinum. It can also be a complex formed from

All patents and patent applications cited herein are hereby incorporated by reference in their disclosure.

A preferred platinum compound for use as a flame retardant additive as well as a platinum catalyst is Karstedt (Ka
rstedt) in French Patent 1,548,775. Generally speaking, this type of platinum complex is formed by reacting chloroplatinic acid containing 4 moles of water of hydration with tetravinylcyclotetrasiloxane in the presence of sodium bicarbonate in an ethanol solution.

One of ordinary skill in the art can easily determine the effective amount of platinum catalyst. Generally, an effective amount is in the range of about 0.1 to 50 ppm of the total organopolysiloxane composition.

In order to impart high tensile strength to the composition of the present invention, particularly when the composition is formed into a thin film or film, it is desirable to incorporate the filler (B) into the composition. Examples of the many fillers that can be used are titanium dioxide, lithopone, zinc oxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, calcium carbonate, fumed silica, silica treated with silazane, precipitated Silica, glass fiber, magnesium oxide, chromic oxide, zirconium oxide, aluminum oxide, α-quartz,
Baked clay, asbestos, carbon, graphite, cork,
There are cotton and synthetic fibers.

The preferred fillers that should be used in the compositions of the present invention are surface treated fumed silica or precipitated silica. In one method of surface treatment, fumed silica or precipitated silica is exposed to cyclic organopolysiloxane under heat and pressure. This surface treatment method is disclosed in US Pat. No. 2,938,009 to Lucas, which is hereby incorporated by reference. Another method of treating the filler is to expose the silica to the siloxane or silane in the presence of an amine compound. This method is disclosed in US Pat. No. 3,024,126, which is incorporated herein by reference.

The preferred method of surface treating the filler is with a methylsilanesilazane surface treating agent. Fillers of fumed silica or precipitated silica surface-treated with methylsilane or silazane flow easily and do not undesirably increase the low clay of the uncured composition. On the contrary, at the same time, the silazane-treated silica filler increases the physical properties of the cured elastomer, in particular the tear strength of the cured elastomer. The best properties are obtained if this silazane treatment is applied to the filler in situ, ie the filler is combined with the composition (A). Fumed silica and precipitated silica treated with silazane are described by Smith in US Pat. No. 3,635,743 and Beer.
s) U.S. Pat. No. 3,847,848, which is hereby incorporated by reference.

The filler (B) is usually used in a concentration of 5 to 70 parts, preferably 15 to 50 parts, per 100 parts by weight of (A). The preferred filler is silazane treated fumed silica or a mixture of silazane treated fumed silica and silazane treated precipitated silica. Such a mixture of silica comprises about 25/1 to about 1/1, preferably about 10/1 to about 5/1 fumed silica and precipitated silica.
Should be contained in a weight ratio of.

The material present in constituent (C) or component 1 is packaged separately from constituent (D) or constituent 2 until it is cured. The constituents (A), (B), (E) and the additives may be distributed to both components or all of them may be added to one component. In this way, an early reaction between storage and transportation is avoided. If one wants to form a cured silicone rubber composition, the two components are mixed together,
The composition is cured by heating at room temperature for 16 hours or by increasing the temperature for a correspondingly shorter curing time.

The mixed components 1 and 2 may be injection molded directly or dissolved in a solvent for application as a film or coating. In injection molding, the mixing barrel and shot chamber must be kept cool to prevent premature curing. Mold temperatures typically range from about 150 ° F to about 500 ° F. Solvents for coating films and coatings include conventional organic solvents for SiH olefin addition reactions of the prior art. Such solvents include, for example, hexane, heptane, pentane, octane, cyclohexane,
Toluene, xylene, acetone and others. Of course, other ingredients may be added to achieve various purposes. Pigments, thixotropic agents, heat stabilizers and the like can be added according to the teachings of the industry. In particular, it is desirable to add inhibitors such as maleates to give the catalyzed material a reasonable pot life. Suitable inhibitors are taught in US Pat. No. 4,256,870 (incorporated herein by reference).

Examples Materials A (1) High viscosity vinyl end-capped organopolysiloxane HVO-82-Dimethyl vinyl end-capped polydimethylsiloxane polymer having a viscosity of 82,000 centipoise at 25 ° C.

HVO-22-A dimethylvinyl-terminated polydimethylsiloxane polymer with a viscosity of 22,000 centipoise at 25 ° C.

HVO-10-A dimethylvinyl end-capped polydimethylsiloxane polymer having a viscosity of 10,400 centipoise at 25 ° C.

A (2) Low-viscosity vinyl-containing organopolysiloxane LVO-316-A dimethylvinyl-terminated polydimethylsiloxane polymer having a viscosity of 316 centipoise at 25 ° C.

LVO-530-a dimethylvinyl-trimethyl terminated polydimethylsiloxane polymer with a viscosity of 530 centipoise at 25 ° C.

(B) Silica Filler Treated with fumed silica-hexamethyldisilazane.

(C) Catalyst Lamoreaux platinum catalyst, octanol complex.

(D) SiH cross-linking agent RHC-a resin hydride cross-linking agent represented by the formula ▲ ^MH ₂ ▼ Q, having a viscosity of 20 centipoise at 25 ° C and H of about 0.9% by weight.

The following examples are given for the purpose of illustrating the invention, but are not meant to limit the scope of the invention described in the claims herein.

Examples 1 to 8 First, liquid injection molding compositions were prepared by adding treated fumed silica to high-viscosity vinyl-containing organopolysiloxane in equal amounts in three portions and mixing them. Mix the resulting batches well and in a full vacuum at 125 ° C
Was heated for 3 hours. The batch was cooled and the other ingredients except the hydride crosslinker were added and mixed until the composition was uniform. The application rate of this hydride crosslinker-free composition was 1 / 8th that of a 90 psig Semco tube.
Tested with an inch nozzle.

A hydride crosslinking agent was added to each liquid injection molding composition.
Add in amounts of 75, 1.0, 1.25 and 1.5 parts by weight. All four samples are cured at 100 ° C for 1 hour. Each of the four samples was tested for hardness, tensile strength, elongation and tear strength. The sample with the highest hardness is selected as representative of the properties of the particular composition. This sample is assumed to have a constant SiH / Vi ratio and maximum hardness in other compositions. In this way the SiH / Vi ratio is kept constant experimentally rather than calculated based on the assumption of vinyl and hydride contents.

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Claims (8)

[Claims] 1. A linear, high-viscosity, vinyl-terminated organoorganic (A) (i) having up to 25 mol% phenyl groups and having a viscosity of 5,000-40,000 centipoise at 25 ° C. 60-75 parts by weight of polysiloxane, and (ii) having at least one terminal vinyl group per molecule, having a vinyl group content which can vary from 0.01 mol% vinyl group to 60 mol% vinyl group, 25 ° C A vinyl group-containing polyorganosiloxane component consisting of 25 to 40 parts by weight of a linear, low-viscosity organopolysiloxane having a viscosity varying from 50 to 2,000 centipoise and having up to 25 mol% of phenyl groups
0 parts by weight, (B) 5 to 70 parts by weight of one kind of the filler or a combination of two or more kinds of the fillers, and (C) a platinum catalyst of 0.
1-50 ppm, and (D) a SiH composition selected from the group consisting of hydrogen-containing silanes and hydrogen-containing organopolysiloxanes of 0.5-
25 parts by weight, and shows a coating speed of at least 100 g / min and 12.3 kgw / c
The SiH composition has a tear strength of m ² (175 psi) or more, and the SiH composition has a unit of the general formula: R _f H _g SiO _{(4-f-g) / 2 in} a number of 0.5 to 99.5%, and Organopolysiloxane having 99.5 to 0.5% by number of units of the formula: R _c SiO _{(4-C) / 2} , where R is a saturated monovalent hydrocarbon radical having up to 20 carbon atoms and It is a saturated and halogenated hydrocarbon group, c has a value of 0 to 3.0, and f is 0 to 2
And the sum of f and g is equal to 1.0 to 3.0], the organopolysiloxane coating composition selected from the group consisting of: 2. The organopolysiloxane end-capped with a high-viscosity vinyl group has the general formula: [Wherein Vi represents a vinyl group, R is selected from the group consisting of monovalent hydrocarbon groups having up to 20 carbon atoms and halogenated monovalent hydrocarbon groups, and x is 100
Can vary from up to 10,000]. 3. The low viscosity organopolysiloxane has the general formula: Wherein R is selected from the group consisting of monovalent hydrocarbon radicals having up to 20 carbon atoms and halogenated monovalent hydrocarbon radicals, R ¹ being the same as R ¹ One R ¹ must be a vinyl group and y is 1 to 300
Variable.] The composition of claim 1, wherein 4. The composition according to claim 3, wherein only ^one of R ¹ is a vinyl group. 5. Component 1 and component 2 packaged separately, (A) (i) having up to 25 mol% of phenyl groups and 25
60 to 75 parts by weight of linear, high-viscosity vinyl-terminated organopolysiloxane having a viscosity of 5,000 to 40,000 centipoise at ℃, and (ii) at least one terminal vinyl group per molecule. , Having a vinyl group content that can vary from 0.01 mol% vinyl groups to 60 mol% vinyl groups, having a viscosity varying from 50 to 2,000 centipoise at 25 ° C., and having up to 25 mol% phenyl groups, 25-40 parts by weight of linear, low-viscosity organopolysiloxane, consisting of 10 parts of vinyl group-containing polyorganosiloxane component
0 parts by weight of all are contained in either component 1 or 2, or partially contained in components 1 and 2, (B) one kind of filler or a combination of two or more kinds of fillers in total 5 to 70 Part by weight is contained in both components 1 and 2 or the whole is contained in one component, and (C) the total amount of the platinum catalyst of 0.1 to 50 ppm of the total organopolysiloxane composition is contained in component 1. And (D) a SiH composition selected from the group consisting of hydrogen-containing silanes and hydrogen-containing organopolysiloxanes 0.5-25
The total amount of parts by weight is contained in component 2, and the coating rate is at least 100 g / min, and 12.3 kgw / c
The SiH composition has a tear strength of m ² (175 psi) or more, and the SiH composition has 0.5 to 99.5% of a unit of the general formula: R _f H _g SiO _{(4-f-g) / 2} , and Organopolysiloxanes having 99.5 to 0.5% by number of units of the formula: R _c SiO _{(4-C) / 2} , where R is a saturated monovalent hydrocarbon radical having up to 20 carbon atoms and It is a saturated and halogenated hydrocarbon group, c has a value of 0 to 3.0, and f is 0 to 2
And the sum of f and g is equal to 1.0 to 3.0], a two-component organopolysiloxane coating composition selected from the group consisting of: 6. The organopolysiloxane end-capped with a high-viscosity vinyl group has the general formula: [Wherein Vi represents a vinyl group, R is selected from the group consisting of monovalent hydrocarbon groups having up to 20 carbon atoms and halogenated monovalent hydrocarbon groups, and x is 100
Can vary from up to 10,000]. 7. The low viscosity organopolysiloxane has the general formula: Wherein R is selected from the group consisting of monovalent hydrocarbon radicals having up to 20 carbon atoms and halogenated monovalent hydrocarbon radicals, R ¹ being the same as R ¹ One R ¹ must be a vinyl group and y is 1 to 300
The composition of claim 5, wherein 8. The composition according to claim 7, wherein only ^one of R ¹ is a vinyl group.