Liquid silicone composition for transfer- or injection-molding optical parts, optical parts made therefrom, and a method thereof

Abstract

Disclosed is a liquid silicone composition for transfer- or injection-molding optical parts. The liquid silicone composition comprises: (A) a linear organopolysiloxane having in a molecule at least two silicon-bonded C.sub.2-10 alkenyl groups and at least one silicon-bonded C.sub.6-20 aryl group; (B) an organopolysiloxane resin represented by a specific average unit formula; (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule; (D) a hydrosilylation reaction catalyst; and (E) a hydrosilylation reaction inhibitor.

Claims

1. A liquid silicone composition for transfer- or injection-molding optical parts, the liquid silicone composition comprising: (A) a linear organopolysiloxane having in a molecule at least two silicon-bonded C.sub.2-10 alkenyl groups and at least one silicon-bonded C.sub.6-20 aryl group; (B) an organopolysiloxane resin represented by the average unit formula:
(R.sup.1SiO.sub.3/2).sub.a(R.sup.1.sub.2SiO.sub.2/2).sub.b(R.sup.1.sub.3SiO.sub.1/2).sub.c(SiO.sub.4/2).sub.d(XO.sub.1/2).sub.e wherein each R.sup.1 is C.sub.1-10 alkyl group, C.sub.2-10 alkenyl group, or C.sub.6-20 aryl group, 0.1 to 40 mol % of R are alkenyl groups, and at least 10 mol % of R.sup.1 are aryl groups; X is a hydrogen atom or C.sub.1-4 alkyl group; and “a” is a positive number, “b” is 0 or a positive number, “c” is 0 or a positive number, “d” is 0 or a positive number, “e” is 0 or a positive number, “b/a” is a number between 0 and 10, “c/a” is a number between 0 and 0.5, “d/(a+b+c+d)” is a number between 0 and 0.3, and “e/(a+b+c+d)” is a number between 0 and 0.4; (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, in a quantity that provides from 0.1 to 10 moles silicon-bonded hydrogen atoms in this component per 1 mole of the total alkenyl groups in components (A) and (B); (D) a hydrosilylation reaction catalyst; and (E) a hydrosilylation reaction inhibitor; wherein a viscosity at 25° C. of the liquid silicone composition is from 25,000 to 50,000 mPa.Math.s, and a scorch time [ts1] as measured by a Moving Die Rheometer (MDR) at 120° C. is from 10 to 50 sec.

2. The liquid silicone composition of claim 1, wherein a weight ratio (A/B) of component (A) to component (B) is from 0.1 to 0.6.

3. The liquid silicone composition of claim 1, wherein component (C) comprises the following components (C-1) and (C-2): (C-1) an organopolysiloxane presented by the following average compositional formula:
(HR.sup.2.sub.2SiO.sub.1/2).sub.f(R.sup.2.sub.3SiO.sub.1/2).sub.g(R.sup.2.sub.2SiO.sub.2/2).sub.h(R.sup.2SiO.sub.3/2).sub.i(SiO.sub.4/2).sub.j(XO.sub.1/2).sub.k wherein each R.sup.2 is C.sub.1-10 alkyl group or C.sub.6-20 aryl group; X is a hydrogen atom or C.sub.1-4 alkyl group; and “f”, “g”, “h”, “i”, “j”, and “k” are numbers that satisfy the following conditions: 0.4≤f≤0.7; 0≤g≤0.2; 0≤h≤0.05; 0≤i≤0.5; 0≤j≤0.6; 0≤k≤0.05; and f+g+h+i+j=1; (C-2) an organopolysiloxane represented by the following average molecular formula:
HR.sup.3.sub.2SiO(R.sup.3.sub.2SiO).sub.mSiR.sup.3.sub.2H wherein each R.sup.3 is C.sub.1-10 alkyl group or C.sub.6-20 aryl group; and “m” is a number in the range of 1 to 100.

4. The liquid silicone composition of claim 1, wherein a weight ratio (D/E) of component (D) to component (E) is from 1 to 30.

5. The liquid silicone composition of claim 1, wherein the composition cures to form a silicone cured product having a type D durometer hardness as specified in ASTM D2240 of from 30 to 70 and an elongation of from 30 to 50%.

6. Transfer- or injection-molding optical parts which are obtained by performing a hydrosilylation reaction of the liquid silicone composition according to claim 1.

7. A method of forming optical parts, the method comprising transfer- or injection-molding the liquid silicone composition according to claim 1.

Description

EXAMPLES

(1) The liquid silicone composition, optical parts produced therefrom, and molding method of the present invention will be further described in more detail, with reference to examples and comparative examples. The viscosity used in the examples is measured at 25° C. Characteristics of a curable liquid silicone composition and optical parts are measured by the methods described below.

(2) MDR Measurement of a Curable Liquid Silicone Composition

(3) The temperature of a measurement device (Rheometry, MDR 2000P, manufactured by Alpha Technologies) was set to the measurement temperature of 120° C. In order to prevent the test piece from making contact with the dies, thin films (Lumirror produced by Toray Industries, Inc., 25 μm) were made to sandwich the test piece from above and below. A 6 g test piece was set in a disc-shaped hollow part of the die constituted by a fixed lower die and an elevating/lowering upper die. The upper and lower dies were hermetically sealed, and the torque value immediately after being hermetically sealed (curing time of 0 seconds) was recorded as the initial torque value under conditions with a frequency of 1.66 Hz and an oscillating angle of 1°.

(4) Hardness of a Cured Body

(5) A cured body is obtained by heating the curable liquid silicone composition for 1 hour at 150° C. in a hot-air-circulation oven. The hardness of the cured body is measured by means of a type D durometer specified by ASTMD 2240.

(6) Tensile Strength

(7) A cured body having the shape of a dumbbell-type specimen No. 3 according to JIS K 6251 is obtained by heating the curable liquid silicone composition for 1 hour at 150° C. in a hot-air-circulation oven. The tensile strength of the cured body is measured with a procedure specified in JIS K 6251.

(8) Resistance to Scratching

(9) The curable liquid silicone composition is poured onto an aluminum plate (55 mm diameter) so as to form a layer with a 1 mm thickness, and the content of the plate is cured by heating at 150° C. for 1 hour in a hot-air-circulation oven. As a result, a plate-like cured body is formed. The surface of this plate is scratched 10 times with a nail, and then the degree of the surface damage is evaluated. The following designations are used for evaluation criteria: ◯-no scratches after 10 times; Δ-scratches after 2 to 10 times; X-scratch after 1 time. Further, the appearance of the sample is observed after treatment for 100 hours at 150° C. in a hot-air-circulation oven.

(10) Index of Refraction through the Curable Liquid Silicone Composition and the Cured Body

(11) Index of refraction through the curable liquid silicone composition at 25° C. is measured with the Abbe refractometer. Measurements are carried out with a visible light (589 nm). Subsequently, the curable liquid silicone composition is then cured by heating for 1 hour at 150° C. in a hot-air-circulation oven, and the index of refraction at 25° C. for the light passing through the obtained cured body is measured in the same manner as for the composition.

(12) Visible Light Permeability through the Curable Liquid Silicone Composition and Cured Body

(13) Visible light permeability through a curable liquid silicone composition (optical path length of 2.0 mm) at 25° C. is measured. Measurements are carried out with visible light with the wavelength of 420 nm. The curable liquid silicone composition is then cured by heating for 1 hour at 150° C. in a hot-air-circulation oven, and permeability of light through the cured body at 25° C. (optical path length of 2.0 mm) is measured.

Example 1

(14) A liquid silicone composition was prepared by uniformly mixing the following:

(15) relative to 100 parts by weight of the curable liquid silicone composition,

(16) 18.69 parts by weight of linear chain methylphenylpolysiloxane having both molecular terminals capped with dimethylvinylsiloxy groups,

(17) 68.47 parts by weight of a branched chain organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.75 [(CH.sub.2═CH)(CH.sub.3).sub.2SiO.sub.1/2].sub.0.25,

(18) 4.20 parts by weight of organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.60[(CH.sub.3).sub.2HSiO.sub.1/2].sub.0.40,

(19) 7.79 parts by weight of organopolysiloxane having the formula: H(CH.sub.3).sub.2SiO[(C.sub.6H.sub.5).sub.2SiO]Si(CH.sub.3).sub.2H,

(20) a complex of platinum with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in such an amount in which 10 ppm in weight units of metallic platinum is comprised, and

(21) 0.85 parts by weight of 2-phenyl-3-butyn-2-ol.

(22) Characteristics of the curable liquid silicone composition and the cured body were measured. The results of measurements were presented in Table 1. Further, lenses were manufactured by using the above-described liquid silicone composition.

Example 2

(23) A liquid silicone composition was prepared by uniformly mixing the following:

(24) relative to 100 parts by weight of the curable liquid silicone composition,

(25) 18.69 parts by weight of a linear chain methylphenylpolysiloxane having both molecular terminals capped with dimethylvinylsiloxy groups,

(26) 68.47 parts by weight of a branched chain organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.75 [(CH.sub.2═CH)(CH.sub.3).sub.2SiO.sub.1/2].sub.0.25,

(27) 4.20 parts by weight of an organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.60[(CH.sub.3).sub.2HSiO.sub.1/2].sub.0.40,

(28) 7.79 parts by weight of organopolysiloxane having the formula: H(CH.sub.3).sub.2SiO[(C.sub.6H.sub.5).sub.2SiO]Si(CH.sub.3).sub.2H,

(29) a complex of platinum with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in such an amount in which 32 ppm in weight units of metallic platinum is comprised, and

(30) 0.85 parts by weight of 2-phenyl-3-butyn-2-ol.

(31) Characteristics of the curable liquid silicone composition and the cured body were measured. The results of measurements are presented in Table 1. Further, lenses were manufactured by using the above-described liquid silicone composition.

Example 3

(32) A liquid silicone composition was prepared by uniformly mixing the following:

(33) relative to 100 parts by weight of the curable liquid silicone composition,

(34) 22.45 parts by weight of a linear chain methylphenylpolysiloxane having both molecular terminals capped with dimethylvinylsiloxy groups,

(35) 64.71 parts by weight of a branched chain organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.75[(CH.sub.2═CH)(CH.sub.3).sub.2SiO.sub.1/2].sub.0.25,

(36) 4.20 parts by weight of an organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.60[(CH.sub.3).sub.2HSiO.sub.1/2].sub.0.40,

(37) 7.79 parts by weight of organopolysiloxane having the formula: H(CH.sub.3).sub.2SiO[(C.sub.6H.sub.5).sub.2SiO]Si(CH.sub.3).sub.2H,

(38) a complex of platinum with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in such an amount in which 32 ppm in weight units of metallic platinum is comprised, and

(39) 0.85 parts by weight of 2-phenyl-3-butyn-2-ol.

(40) Characteristics of the curable liquid silicone composition and the cured body were measured. The results of measurements are presented in Table 1. Further, lenses were manufactured by using the above-described liquid silicone composition.

Comparative Example 1

(41) A composition was prepared by uniformly mixing the following:

(42) relative to 100 parts by weight of a curable liquid silicone composition,

(43) 63 parts by weight of a linear chain dimethylpolysiloxane having both molecular terminals capped with dimethylvinylsiloxy groups,

(44) 30 parts by weight of a branched chain organopolysiloxane having the average unit formula: (SiO.sub.4/4).sub.0.55[(CH.sub.2═CH)(CH.sub.3).sub.2SiO.sub.1/2].sub.0.45,

(45) 5 parts by weight of a polymethylhydrogensiloxane end blocked at both molecular chain terminals by trimethylsiloxy groups with a kinematic viscosity of 21 mm.sup.2/s and a silicon-bonded hydrogen atom content of 1.57% by mass,

(46) a complex of platinum with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in such an amount in which 32 ppm in weight units of metallic platinum is comprised, and

(47) 0.85 parts by weight of 2-phenyl-3-butyn-2-ol.

(48) Characteristics of the curable liquid silicone composition and of the cured body were measured. The results of measurements are presented in Table 1. Further, lenses were manufactured by using the above-described liquid silicone composition.

Comparative Example 2

(49) A liquid silicone composition was prepared by uniformly mixing the following:

(50) relative to 100 parts by weight of the curable liquid silicone composition,

(51) 20.39 parts by weight of a linear chain methylphenylpolysiloxane having both molecular terminals capped with dimethylvinylsiloxy groups,

(52) 66.77 parts by weight of a branched chain organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.75[(CH.sub.2═CH)(CH.sub.3).sub.2SiO.sub.1/2].sub.0.25,

(53) 4.20 parts by weight of an organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.60[(CH.sub.3).sub.2HSiO.sub.1/2].sub.0.40,

(54) 7.79 parts by weight of organopolysiloxane having the formula: H(CH.sub.3).sub.2SiO[(C.sub.6H.sub.5).sub.2SiO]Si(CH.sub.3).sub.2H,

(55) a complex of platinum with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in such an amount in which 6 ppm in weight units of metallic platinum is comprised, and

(56) 0.85 parts by weight of 2-phenyl-3-butyn-2-ol.

(57) Characteristics of the curable liquid silicone composition and the cured body were measured. The results of measurements are presented in Table 1. Further, lenses were manufactured by using the above-described liquid silicone composition.

Comparative Example 3

(58) A liquid silicone composition was prepared by uniformly mixing the following:

(59) relative to 100 parts by weight of the curable liquid silicone composition,

(60) 20.39 parts by weight of a linear chain methylphenylpolysiloxane having both molecular terminals capped with dimethylvinylsiloxy groups,

(61) 66.77 parts by weight of a branched chain organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.75[(CH.sub.2═CH)(CH.sub.3).sub.2SiO.sub.1/2].sub.0.25,

(62) 4.20 parts by weight of an organopolysiloxane having the average unit formula: (C.sub.6H.sub.5SiO.sub.3/2).sub.0.60[(CH.sub.3).sub.2HSiO.sub.1/2].sub.0.40,

(63) 7.79 parts by weight of organopolysiloxane having the formula: H(CH.sub.3).sub.2SiO[(C.sub.6H.sub.5).sub.2 SiO]Si(CH.sub.3).sub.2H,

(64) a complex of platinum with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in such an amount in which 46 ppm in weight units of metallic platinum is comprised, and

(65) 0.85 parts by weight of 2-phenyl-3-butyn-2-ol.

(66) Characteristics of the curable liquid silicone composition and the cured body were measured. The results of measurements are presented in Table 1. Further, lenses were manufactured by using the above-described liquid silicone composition.

(67) [Preparation Example of Lens]

(68) Lenses were made by means of the conventional transfer-molding method.

(69) By injecting a silicone composition in the liquid state due to high temperature into a cavity in a molding die having an upper die with a port and a lower die with the application of a constant temperature and pressure through a runner of the molding die and by curing the same, lenses were prepared.

(70) The applied pressure was 1.5 bar and the temperature was 120° C.

(71) The results of transfer-molding are shown in Table 1.

(72) TABLE-US-00001 TABLE 1 Examples Examples Comparative Examples Characteristics 1 2 3 1 2 3 Curable Liquid Silicone Composition Index of Refraction 1.54 1.54 1.54 1.41 1.54 1.54 Light Permeability (%) (in 2 mm) 90 90 90 93 90 90 Viscosity (cps) 40,000 40,000 22,000 26,000 35,000 35,000 Scorch time (sec.) at 120° C. 34 18 16 27 51 8 Cured Body Hardness (Shore D) 55 55 55 25 50 50 Tensile Strength (MPa) 5.2 5.2 5.2 12.7 5.2 5.2 Resistance to Scratching ◯ ◯ ◯ X ◯ ◯ Index of Refraction 1.54 1.54 1.54 1.41 1.54 1.54 Light Permeability (%) (in 2 mm) 90 90 90 93 90 90 Transfer Molding Process Time of Process (sec) 150 240 260 180 350 180 Leakage Area (cm.sup.2) 5.2 18 77 6.2 24.3 6.1 Short Shot (%) 2% 2% 2% 2%  3%  8% Void (%) Less 5% 8% 2% 12% 19% than 2% Rate of Releasing of Molded Less Less Less Less Less Less Articles(%) than 1% than 1% than 1% than 1% than 1% than 1%

INDUSTRIAL APPLICABILITY

(73) The curable liquid silicone composition of the present invention is suitable as a material for producing optical parts such as a lens. The optical parts prepared from the composition show a high index of refraction and have an advantage in that they can lower the rate of defected products during the process of preparation.