CN-117203286-B - Resin composition and optical element

Abstract

The invention aims to provide a resin composition capable of forming an optical element with high transparency and low birefringence while suppressing the generation of molding defects such as wiredrawing. The resin composition of the present invention comprises an alicyclic structure-containing polymer and a strontium carbonate powder, and the content of the strontium carbonate powder in the resin composition is 0.2 mass% or more and 1.0 mass% or less.

Inventors

• SAWAGUCHI TAICHI

Assignees

• 日本瑞翁株式会社

Dates

Publication Date

20260508

Application Date

20220523

Priority Date

20210531

Claims (5)

1. 1. A resin composition comprising an alicyclic structure-containing polymer and strontium carbonate powder, The content of the strontium carbonate powder in the resin composition is 0.2 to 0.4 mass% or more and 0.65 to 0.8 mass%, The alicyclic structure-containing polymer is a polymer obtained by polymerizing an alicyclic structure-containing monomer which is one or more selected from the group consisting of alicyclic structure-containing monomers having one, two, three, four and five rings and derivatives of the alicyclic structure-containing monomers having a substituent on the ring, wherein the substituent on the ring of the derivatives is an alkyl group, an alkylene group, a vinyl group, an alkoxycarbonyl group or an alkylidene group, The strontium carbonate powder comprises strontium carbonate nano-particles and a surfactant attached to the surfaces of the strontium carbonate nano-particles, The content of the surfactant is 1 to 40 parts by mass based on 100 parts by mass of the strontium carbonate nanoparticles, The alicyclic structure-containing polymer comprises a structural unit derived from the alicyclic structure-containing monomer, optionally a structural unit derived from a monomer other than the alicyclic structure-containing monomer, The mass ratio of the amount of the other monomer to the amount of the alicyclic structure-containing monomer, that is, the ratio of the amount of the other monomer to the amount of the alicyclic structure-containing monomer, is 30/70 or less.
2. 2. The resin composition according to claim 1, wherein a melt flow rate measured at a temperature of 280 ℃ and a load of 21.18N according to JIS K6719 is 40g/10min or more.
3. 3. The resin composition according to claim 1 or 2, wherein the aspect ratio of the strontium carbonate powder is 1.1 or more.
4. 4. The resin composition according to claim 1 or 2, wherein the content ratio of the strontium carbonate powder in the resin composition is 0.2 mass% or 0.75 mass%.
5. 5. An optical element molded from the resin composition according to claim 1 or 2.

Description

Resin composition and optical element Technical Field The present invention relates to a resin composition and an optical element. Background Optical members are required to have excellent optical characteristics such as transparency and birefringence, and weather resistance such as moisture resistance and heat resistance. Examples of the material of the optical member include alicyclic structure-containing polymers such as cycloolefin polymers, polycarbonates, polyethylene terephthalate, and polyacrylates. In recent years, various materials have been proposed in order to obtain an optical member having more excellent optical characteristics. For example, patent document 1 proposes that an optical member such as a film used in a bent state is made of an optical resin containing an alkaline earth metal carbonate fine powder in order to adjust birefringence of the optical member. According to patent document 1, since the alkali earth metal carbonate fine powder itself is a birefringent powder, the birefringence of the optical member can be controlled. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2021-47402. Disclosure of Invention Problems to be solved by the invention Here, a resin composition for forming an optical element such as a lens is required to exhibit high transparency and low birefringence when molded into an optical element. In addition, when an optical element such as a lens can be formed by injection molding a resin composition, it is also required that such a resin composition can suppress occurrence of molding failure such as stringing. Accordingly, an object of the present invention is to provide a resin composition capable of forming an optical element having high transparency and low birefringence while suppressing occurrence of molding failure such as stringing, and an optical element formed by molding the resin composition. Solution for solving the problem The present inventors have conducted intensive studies with a view to solving the above-mentioned problems. The present inventors have found that, when the resin composition contains an alicyclic structure-containing polymer and a strontium carbonate powder and the content ratio of the strontium carbonate powder is within a specific range, the occurrence of molding defects such as stringing can be suppressed and an optical element having high transparency and low birefringence can be formed, and completed the present invention. Specifically, an object of the present invention is to solve the above-mentioned problems, and [1] the resin composition of the present invention comprises an alicyclic structure-containing polymer and a strontium carbonate powder, wherein the content of the strontium carbonate powder in the resin composition is 0.2 mass% or more and 1.0 mass% or less. In the case of such a resin composition, the occurrence of molding defects such as stringing is suppressed, and an optical element having high transparency and low birefringence can be formed. [2] The resin composition according to item [1] above, wherein the strontium carbonate powder preferably comprises strontium carbonate nanoparticles and a surfactant attached to the surface of the strontium carbonate nanoparticles. In the case of such strontium carbonate powder, the dispersibility of the strontium carbonate powder in the resin composition can be improved. [3] The resin composition of [1] or [2] above preferably has a melt flow rate of 40g/10min or more as measured according to JIS K6719 at a temperature of 280℃and a load of 21.18N. In the case of the resin composition having the melt flow rate of at least the lower limit, the birefringence of the obtained optical element can be further reduced. In addition, if the melt flow rate is equal to or higher than the lower limit, the occurrence of molding defects such as weld lines can be suppressed. [4] The resin composition according to any one of [1] to [3], wherein the aspect ratio (ratio of average long diameter to average short diameter) of the strontium carbonate powder is preferably 1.1 or more. If the aspect ratio of the strontium carbonate powder is not less than the lower limit, birefringence of the obtained optical element can be effectively suppressed. In the present specification, the average major axis and the average minor axis of the strontium carbonate powder are measured by a method of automatically image-processing a scanning electron microscope photograph of the strontium carbonate powder. [5] The resin composition according to any one of [1] to [4], wherein the average diameter of the strontium carbonate powder is preferably 10nm or more and 100nm or less. If the average diameter of the strontium carbonate powder is not less than the lower limit, the decrease in transparency of the obtained optical element can be controlled. On the other hand, if the average diameter of the strontium carbonate powder is less than the upper limit, the surface