阅读说明：本技术 可缩合固化组合物 (Condensation curable composition ) 是由 T·迪米特洛娃 A-M·万斯蒂芬奥德特 于 2019-03-15 设计创作，主要内容包括：本发明公开了一种缩合固化有机硅氧烷组合物,所述缩合固化有机硅氧烷组合物可用作电绝缘密封剂和/或粘合剂。所述组合物为有机硅弹性体组合物,所述有机硅弹性体组合物包含：a)聚二有机硅氧烷,每分子所述聚二有机硅氧烷具有至少两个-OH或能水解基团b)交联剂,所述交联剂将使所述聚二有机硅氧烷(a)交联；c)填料组分,所述填料组分包含(ii)所述组合物的最多25重量％的碳酸钙和/或二氧化硅,以及(ii)一定量的一种或多种纤维填料,所述一种或多种纤维填料选自矿物纤维、散纤维、耐火纤维、玄武岩纤维或它们的混合物d)缩合固化催化剂以及任选的e)一种或多种添加剂,所述有机硅弹性体组合物在固化时提供具有≥2×10<Sup>15</Sup>Ω.cm的体积电阻率的有机硅弹性体。(A condensation-cure organosiloxane composition useful as an electrically insulating sealant and/or adhesive is disclosed, the composition being a silicone elastomer composition comprising a) a polydiorganosiloxane having at least two-OH or hydrolysable groups per molecule b) a crosslinker that will crosslink the polydiorganosiloxane (a), c) a filler component comprising (ii) up to 25 wt% calcium carbonate and/or silica of the composition, and (ii) an amount of one or more fibrous fillers selected from mineral fibers, bulk fibers, fire resistant fibers, basalt fibers, or mixtures thereof d) a condensation-cure catalyst and optionally e) one or more additives that when cured provide a silicone elastomer composition having ≥ 2 × 10 15 A silicone elastomer having a volume resistivity of Ω.)

1. A silicone elastomer composition, comprising:

a) polydiorganosiloxane having at least two-OH or hydrolysable groups per molecule

b) A crosslinking agent which will crosslink the polydiorganosiloxane (a);

c) a filler component comprising

(i) Up to 25% by weight of the composition of calcium carbonate and/or silica, and

(ii) an amount of one or more fibrous fillers selected from mineral fibers, loose fibers, refractory fibers, basalt fibers or mixtures thereof

d) Condensation curing catalyst and optionally

e) One or more additives selected from the group consisting of,

the silicone elastomer composition, when cured, provides a silicone elastomer composition having a surface tension of 2 × 10 or more¹⁵A silicone elastomer having a volume resistivity of Ω.

2. The silicone elastomer composition of claim 1, wherein component (c) (i) comprises precipitated or ground calcium carbonate and/or fumed hydrophobic silica, in each case preferably having>100m²BET specific surface area in g.

3. The silicone elastomer composition according to any preceding claim, wherein component (c) (ii) comprises one or more fibrous fillers selected from fibers consisting of one or more alkali metal oxides, alkaline earth metal oxides, aluminum oxide and iron oxide and mixtures thereof.

4. The silicone elastomer composition according to any preceding claim, wherein component (c) (ii) comprises one or more fibrous fillers consisting essentially of SiO₂Transition metal oxides, oxides of the alkali elements and alkaline earth elements.

5. The silicone elastomer composition according to any preceding claim, wherein component (c) (ii) comprises one or more ceramic or refractive fibers having a fiber length of from 100 microns to 150 microns and a CaO/MgO content of less than 30 wt% of the total weight of (c) (ii).

6. The silicone elastomer composition according to any preceding claim, wherein component (c) (i) is treated with a treating agent selected from one or more of a fatty acid or fatty acid ester such as a stearate or with an organosilane, organosiloxane or organosilazane, for example hexaalkyldisilazane or short chain siloxane diol to render the filler hydrophobic.

7. The silicone elastomer composition according to any preceding claim, wherein filler component (c) may be present in an amount of 10 wt.% to 50 wt.% of the composition.

8. The silicone elastomer composition according to any preceding claim, wherein filler component (c) is present from about 5% to 15% by weight of the composition of a filler of type (c) (i) and from 15% to 40% by weight of the composition or from 15% to 30% by weight of the composition of a fibrous filler of type (c) (ii).

9. The silicone elastomer composition according to any preceding claim, wherein the composition is stored in at least two parts prior to use.

10. The silicone elastomer composition according to claim 9, wherein

The first part is a base composition comprising a polymer (a), a reinforcing filler (c) and a filler treating agent;

and the second part is a curing agent.

11. A silicone elastomer obtainable by curing a composition according to any one of claims 1 to 10 or obtainable by curing a composition according to any one of claims 1 to 10, the silicone elastomer having ≥ 2 × 10¹⁵Volume resistivity of Ω · cm.

12. A method of preparing a silicone elastomer from the composition of any one of claims 1 to 10 by curing the composition.

13. The method of claim 12, wherein the filler is treated in situ with the filler treating agent.

14. The method of preparing a silicone elastomer according to claim 12 or 13, wherein the composition is stored in at least two parts prior to use.

15. Use of a carboxylated liquid organic polymer as filler treatment in a composition according to any of claims 1 to 10.

16. The use of claim 15, wherein the carboxylated liquid organic polymer comprises a carboxylated liquid polyalkadiene.

17. Use according to claim 15 or 16, wherein the carboxylated liquid organic polymer is selected from carboxylated liquid polyisoprene, carboxylated liquid polypropylene, carboxylated liquid polybutadiene and/or carboxylated liquid polyhexamethylene and/or carboxylated liquid polyalkadiene copolymer; or comprises a carboxylated liquid polyalkadiene.

18. Use of the silicone elastomer according to claim 11 as a sealant and/or adhesive.

Examples

The components used

Polydiorganosiloxanes polymers (a) having different average Degrees of Polymerization (DP) were used, as shown in the following table. Unless otherwise indicated, they are typically polydimethylsiloxanes having dimethylhydroxy end groups. The DP of the polymers utilized was determined by Gel Permeation Chromatography (GPC) with an accuracy of about 10% to 15%. As previously discussed, this technique is standard and yields Mw (weight average molecular weight), Mn (number average molecular weight), and Polydispersity Index (PI). PI-Mw/Mn value, as previously discussed. DP is related to the viscosity of the polymer, with higher DP the higher the viscosity. Typically, for Mw between 13000 and 70000, the relationship between viscosity and Mw is Log (viscosity) ═ 3.70Log (Mw) -16.3.

CaCO used in the examples with stearic acid₃(c) (i) performing a surface treatment. According to the manufacturer's data, the mean particle size is 60 to 70 μm and the BET surface area is 18m²G to 20m²/g。

Fibrous filler

The fibrous fillers (c) (ii) used in the following examples are commercial productsSH、

1000、1000 andCF50。

SH is available from Morgan Ceramics, Inc., and others from Lapinus fibers BV. Tables 1a to 1c below summarize the compositions and some properties of the fibres used, which are provided in the technical data tables thereof. The fibres consisting essentially of SiO₂Transition metal oxides, oxides of alkali elements and alkaline earth elements.

Table 1a minimum weight% of mineral oxides present in different fibers

Unknowns (i.e., the vendor is not provided in the data sheet)

Tracking digital details not provided in supplier data sheets

Table 1b maximum weight% of mineral oxides present in different fibers%

Table 1c physical properties of the fibrous fillers used in the examples

The non-reinforcing silica may be both fumed silica and precipitated silica. The inventors have found that it is beneficial to use silica having a hydrophobic surface to facilitate incorporation into the matrix. Examples include (not to be exhaustive list)R9200、

D10、

D13 andd17, both available from Evonik Industries, Inc.

The adhesion promoters used are carbasilatrane derivatives, which are condensation products of reactive silanes, and are prepared as described in paragraph [0047] of WO2007037552a2 (adhesion promoter a), assigned to Dow Corning corporation.

The tin-based catalyst (d) is tin dimethyldineodecanoate, DMTDN

The foregoing ingredients are illustrated below by the following examples, in which the compositions are provided in weight percent (wt%), unless otherwise indicated. Use of

The viscosity was measured with a cone-plate viscometer (RVDIII), and the speed was adjusted according to the polymer viscosity using a cone-plate CP-52 for a viscosity of 40,000mPa.s or less and a cone-plate CP-51 for a material having a viscosity of more than 40,000 mPa.s.

The volume resistivity of a typical calcium carbonate filled two-part sealant formulation was used as a reference. The composition of the base and curing agent portions is shown below. The base part and the curing agent part were mixed together in a 10:1 ratio at a volume ratio of 10: 1.

TABLE 2a

TABLE 2b

Sample preparation for measurement of volume resistivity:

a 2mm thick sheet was prepared as follows: the base and curing agent were mixed in the appropriate ratio and placed between two teflon foils. The foils were then pressed against each other using a hydraulic press (Agila) operating at room temperature of 23 ℃ +/-1 ℃. The protective sheet thus obtained was cured under controlled conditions (25 ℃ and 50% relative humidity) for 3 weeks. The foil was then removed and square pieces were cut out of the cured sheet for volume resistivity measurements.

For the purposes of the present invention, the volume resistivity was measured 5 minutes after applying a 500V current. The experiments were carried out at room temperature from 21 ℃ to 23 ℃ and at a relative humidity of 50 +/-10%. The reported values are the average of 3 independent measurements.

Volume resistivity was determined using a 16008B resistivity cell supplied by Keysight Technologies, Inc. in combination with a 4339B high resistivity meter DC of the same supplier, the apparatus is suitable for accurately measuring up to 1.6 × 10, depending on the supplier of the apparatus¹⁶Volume resistance value of Ω · cm.

The reference elastomeric material made from the two-part composition shown in tables 2a and 2b above is given a value of 1.3 × 10¹⁵A value of less than 2.0 × 10, as required herein¹⁵And are therefore unsuitable for use in an electronic environment.

Examples of the inventive formulations

All compositions are in parts by mass. Therefore, the sum is not necessarily 100.

Table 3a formulations: foundation

Preparation of the base

It has been determined that the following proves to be the most effective order of addition for preparing the above-mentioned matrix material:

a siloxane polymer;

filler treating agent

-a filler.

The base was prepared using a Hauschield DAC 400.1FVZ type mixer, but alternatively a planetary mixer could be used.

TABLE 3b formulation curing agent

Preparation of the curing agent

Curing agent compositionR974 is hydrophobic fumed silica post-treated with dimethyl-dichloro-silane from Evonik Industries. According to the technical data sheet, the specific surface area is 200m²/g。

It has been determined that the preferred order of addition of the curative components is as follows:

-siloxane polymers

-a particulate filler

-adhesion promoters

-aminoethyl-aminopropyl-trimethoxysilane (distillation)

-methyltrimethoxysilane

-1, 6-bis (trimethoxysilyl) hexane

DMTDN, followed by degassing at-500 mbar (-50kPa)

Curing agents are typically prepared using a Hauschield DAC 400.1FVZ type mixer, but alternatively a planetary mixer may be utilized.

The inventors have found that this order of addition ensures the best homogeneity.

The following table identifies the combinations used for each example and provides the corresponding volume resistivity results for each example. It is noted that each of the embodiments is>2×10¹⁵Ohm.cm

TABLE 3c

1) By using

SH and

1000, best results are obtained with the same fiber content, both characteristic fiber lengths being in the range of 100 to 150 microns.

2)SH andcomparison of CF50 (equivalent dose) shows CaO/MgO or Al₂O₃The presence of (or both) can adversely affect the resistivity.

3)CF50 and

1000 (similar fiber length, same Al)₂O₃Content) shows that higher CaO/MgO content adversely affects the resistivity.

Durable adhesion:

durability of protective coatings

The feasibility of adhesives in practice requires materials that provide durable adhesion. The manner in which this is modeled is to perform one or more accelerated weathering tests. For purposes of this disclosure, "durable adhesion" means that once cast on a substrate and cured, the adhesive is able to withstand three weeks of weathering without exhibiting more than 50% adhesive failure in the final step (step 3 below). (method 1).

Alternatively (method 2) adhesion durability can be evaluated using an adhesion durability test piece (as described in method 2 below). This method also provides mechanical properties of the adhesive, which is an advantage. Method 2 is time consuming because it dictates a 30 day cure, while method 1 allows poor (poor performing) adhesives to be discarded after one or two weeks of aging.

Method 1

Adhesion Failure (AF) refers to the condition when the coating cleanly separates (peels) from the substrate. Cohesive Failure (CF) is observed when the coating itself breaks without separating from the substrate (e.g., steel sheet). In some cases, a hybrid failure mode may be observed; i.e. some areas are stripped off (i.e. AF) and some areas remain covered by a coating (i.e. CF). In such cases, the surface has been determined to show portions of CF (% CF) and AF (% AF) behavior. The sum of% CF +% AF is 100%.

The adhesion test sequence defining durability (i.e., the three week weathering test) is thus described and performed on physically identical test specimens in the following sequence. When several samples are tested (replicated), at least 75% of them are required to pass. If the specimen does not pass step 1 or step 2, the experiment is stopped because the adhesion of the material is considered to be insufficient.

Step 1: room Temperature (RT) for one week (RT from 20 ℃ to 25 ℃) and relative humidity of about 50%. 100% cohesive failure is necessary

Step 2. Room Temperature (RT) for one week (RT from 20 ℃ to 25 ℃) and complete immersion in water followed by drying at RT and about 50% relative humidity for 24 hours. 100% cohesive failure is necessary

Step 3. elevated temperature for one week (this is between 45 ℃ and 55 ℃) and fully immersed in water, followed by drying at RT and about 50% relative humidity for 24 hours. At least 50% cohesive failure was necessary to apply a fresh mixture of base + curing agent at the ratio specified in table 3c over an area of about 6 x 4cm on a stainless steel test substrate to form a layer +/-6mm thick. The composition was then cured at Room Temperature (RT) for 7 days. Subsequently, a 0.5cm undercut was made as close to the steel plate as possible. The cured coating was then pulled apart manually and the failure type was recorded (step 1).

A suitable material should withstand the entire sequence of 3 adhesion tests.

Method 2

The adhesion durability test piece (also referred to as "H-type test piece") was prepared by filling an admixture, which was prepared by mixing a separately stored base and a curing agent composition, between two 4 × 5cm aluminum plates. The dimensions of the H pieces conform to the specifications of the EOTA-ETAG 002 (5 months 2012) document (page 32). Commercial OS1200 primer from dow chemical is applied in some cases before the H pieces are prepared. Pieces H were allowed to cure for 30+/-4 days. The adhesion durability test pieces were evaluated by measuring both the tensile stress and the elongation at break required to break the pieces, according to the method described in the EOTA-ETAG 002 (5 months 2012) document. In addition, failure modes were assessed by visual observation. More specifically, the surface percentage (% CF) corresponding to cohesive failure was evaluated. When the entire surface of the silicone rubber underwent cohesive failure, the CF rate was assumed to be 100%. When peeling was observed on the entire surface, the CF rate was 0%.

The accelerated aging test was performed as follows: pieces H were cured at RT and 50% RH for 7 days. The cured H pieces were then stored in water at 45 ℃ for seven days and then allowed to recover for 2 days before mechanical testing.

Adhesion was considered sufficient when the H bars cured for 30+/-4 days exhibited at least 90% CF and the specimens subjected to accelerated aging exhibited at least 50% CF.

Adhesion method 1

TABLE 4

Foundation	Example 1	Example 8
			Curing agent	CA1	CA2
Ratio of base to curing aging (quality)	3.8:1	6:1
			7 days at Room Temperature (RT) (D)	100％CF	100％CF
7D RT +7D Water at 23 ℃	100％CF	100％CF
			7D RT +7D Water at 23 ℃ plus 7D Water at 45 ℃	100％CF	100％CF

Adhesion method 2

TABLE 5

Tensile measurements at break and elongation at break measurements were made according to ASTM D412-98 a.

It can be concluded that the material of the present invention will be higher than 2.0 × 10¹⁵Cm volume resistivity is combined with durable adhesion because the samples show 100% CF (e.g., greater than 90% CF) after 33 days of cure, and the samples subjected to accelerated aging exhibit at least 90% CF (e.g., greater than 50% CF). The sample also passed the test criteria of method 1.