JP2017043642A - Photocurable resin composition for gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocurable resin composition for a gasket rich in elasticity, capable of holding its shape for a long period of time even after application because of high thixotropic ratio and extremely low in moisture vapor permeability.SOLUTION: There is provided a photocurable resin composition for a gasket containing (a) urethane (meth)acrylate of 10 to 60 wt.%, (b) rosin ester of 1 to 35 wt.%, (c) a thixotropy-imparting agent of 1 to 15 wt.%, (d) a (meth)acrylate monomer of 20 to 70 wt.% and (e) a photoinitiator of 0.1 to 10 wt.%, and the (a) component contains (a1) urethane (meth)acrylate having a polyether-based skeleton and (a2) urethane (meth)acrylate having a polybutadiene-based skeleton.SELECTED DRAWING: None

Description

  The present invention relates to a photocurable resin composition for gaskets.

  Generally, a photo-curing resin is a solvent-free material that is environmentally friendly, can be cured in a short time, and is very easy to handle. It is also easy to adjust the design of the resin, and it is possible to improve the hardness and heat resistance by introducing a cross-linked structure, or conversely, to lower the cross-link density to give flexibility. For this reason, photo-curing resins are widely used for electronic and electrical parts, printing, painting, and the like.

  Patent Document 1 includes (A) urethane (meth) acrylate 10 to 80% by weight, (B) (meth) acrylic acid ester monomer 20 to 90% by weight, and (C) photopolymerization initiator 0.3 to 10% by weight. (D) A photocuring characterized in that it is a composition comprising 1 to 30% by weight of a filler as a main component, and the composition has a yield value (yield stress) in a range of a shear stress of 5 to 100 Pa. A sealant composition is disclosed.

JP-A-2005-139461

  Conventionally, a photocurable resin is produced by irradiating light to a monomer having an unsaturated bond. However, even after excessive light irradiation, the total amount of monomer is not completely cured, and a trace amount of monomer remains. And a very small amount of volatile monomer called outgas is generated, which corrodes internal electronic components and causes malfunction. As an example of solving this problem, the invention of Patent Document 1 can be cited. However, after photocuring, the moisture permeability, which is a ratio of passing moisture in the air, tends to be extremely high, and electronic devices such as hard disk drives are used. When used as a gasket in a product, there is a problem that the performance of the electronic product itself is remarkably inferior due to insufficient performance, and there is room for improvement.

  The present invention includes (a) 10 to 60% by weight of urethane (meth) acrylate, (b) 1 to 35% by weight of rosin ester, (c) 1 to 15% by weight of a thixotropic agent, And 20) to 70% by weight of (meth) acrylate monomer, and 0.1 to 10% by weight of (e) photopolymerization initiator, and the component (a) has (a1) a polyether skeleton. A photocurable resin composition for a gasket, comprising urethane (meth) acrylate and (a2) urethane (meth) acrylate having a polybutadiene skeleton.

  The photocurable resin composition of the present invention is rich in elasticity and has a high thixo ratio, so that it can maintain its shape for a long time even after application, and has extremely low moisture permeability. Suitable for gaskets in electronic products.

  In the present invention, (a) urethane (meth) acrylate is used. Urethane (meth) acrylate can be synthesized from a polyol compound, a (meth) acrylate compound having a functional group reactive with an isocyanate group, and a polyfunctional isocyanate compound. In the photocurable resin composition of the present invention, It is a raw material that is the main component.

  The component (a) needs to be used in an amount of 10 to 60% by weight, preferably 15 to 50% by weight, particularly preferably 20 to 35% by weight, based on all the ingredients. By adding at this blending ratio, a resin composition having a viscosity suitable for gaskets can be obtained.

  Here, as a kind of urethane (meth) acrylate, what has frame | skeletons, such as a polyether type, a polycarbonate type, a polyester type, a polybutadiene type, is mentioned. In the present invention, in order to achieve both high elasticity and low moisture permeability, (a1) urethane (meth) acrylate having a polyether skeleton, and (a2) urethane (meth) acrylate having a polybutadiene skeleton, Need to be used together.

  Specific examples of the component (a1) include SX15-20 (Asia Kogyo Co., Ltd., trade name), SUA-008 (Asia Kogyo Co., Ltd., trade name), RX8-101 (Asia Kogyo Co., Ltd.) as commercially available products. ), Product name), RX8-76 (Asia Kogyo Co., Ltd., product name) and the like. Moreover, as a specific example of (a2) component, TE2000 (Nippon Soda Co., Ltd., brand name), BAC-45 (Osaka Organic Chemical Co., Ltd., brand name) etc. are mentioned as a commercial item.

  As the blending ratio of the components (a1) and (a2), it is preferable to use 1 to 80 parts by weight of the component (a2), particularly 20 to 50 parts by weight based on 100 parts by weight of the component (a1). preferable. By mix | blending in this ratio, the elasticity of a resin composition can be made higher and a water vapor transmission rate can be made lower.

  The component (a1) has a number average molecular weight of less than 10,000, preferably a urethane (meth) acrylate having a polyether skeleton having a number average molecular weight of 10,000 or more and 3,000 or more and less than 10,000. Thus, it is preferable to include urethane (meth) acrylate having a polyether skeleton that is preferably 10,000 or more and less than 20,000. Moreover, as each compounding ratio, it is preferable to use 10-300 weight part of the latter with respect to 100 weight part of the former, and it is especially preferable to use 30-250 weight part.

  Next, in the present invention, (b) rosin ester is used. This is an ester that can be synthesized based on a rosin obtained from rosin or the like, and is mainly used as a tackifier in an adhesive or the like. In the present invention, the moisture permeability can be drastically reduced by blending with the resin composition.

  The component (b) needs to be used in an amount of 1 to 35% by weight, preferably 3 to 33% by weight, particularly preferably 5 to 31% by weight, based on all the ingredients. If it is 1% by weight or more, the moisture permeability tends to decrease, and if it is within 35% by weight, only the component (b) does not separate and precipitate.

  In the present invention, (c) a thixotropic agent can be used. Thixotropic agents are often used for the purpose of increasing the thixo ratio. In the present invention, dripping can be remarkably suppressed by blending into the resin composition. Therefore, even if the photocurable resin composition according to the present invention is applied to the member and then left for a while, there is an effect that the risk of dripping and flowing out is eliminated.

  Specific examples of the (c) thixotropic agent include inorganic ones such as calcium carbonate, aluminum hydroxide, silica and titanium oxide, organic ones such as hydrogenated castor oil, fatty acid amide and polyethylene oxide, carboxymethylcellulose. Examples of the polymer include sodium and xanthan gum. Generally, when a thixotropy imparting agent is added, curability tends to deteriorate in the deep part of the composition, but this tendency is preferably suppressed by using an inorganic thixotropy imparting agent, particularly silica. I can do it.

  The inorganic thixotropic agent can be used as it is, but may be added after adding a coupling agent and subjecting it to a surface treatment. Examples of the coupling agent include a silane coupling agent and a titanium coupling agent, but it is preferable to use a silane coupling agent from the viewpoint of reactivity and compatibility with other components. Examples of the silane coupling agent include (meth) acrylic, vinyl, epoxy, amino, thiol, and silicone types. As a surface treatment method, for example, there is a method of obtaining hydrophobic silica by adding a silane coupling agent to silica and treating it by a dry method or a wet method.

  The component (c) needs to be used in an amount of 1 to 15% by weight, preferably 3 to 13% by weight, and particularly preferably 5 to 10% by weight, based on all the ingredients. When it is 1% by weight or more, the thixo ratio can be increased, and when it is within 15% by weight, uncured deep portions can be prevented when the resin composition is photocured.

  Furthermore, in the present invention, it is necessary to use (d) (meth) acrylate monomer in order to optimize the thixo ratio and moisture permeability. The component (d) needs to be used in an amount of 20 to 70% by weight, preferably 25 to 60% by weight, and particularly preferably 30 to 50% by weight, based on all the ingredients. By mix | blending in this range, the water vapor transmission rate of a resin composition can be reduced significantly.

  As the component (d), (d1) a (meth) acrylate monomer containing a linear or branched alkyl group as a substituent, (d2) a (meth) acrylate monomer containing a cyclic alkyl group as a substituent (D3) One or more components selected from the group consisting of (meth) acrylate monomers containing a hydroxyl group can be used. In particular, it is preferable to use two or more components among the (d1) component, the (d2) component, and the (d3) component because a higher effect can be obtained. When all three components are used in combination, a higher effect can be obtained. More preferred. However, when the component (d) contains an ether skeleton, the moisture permeability of the composition tends to increase, which is not preferable.

  As the component (d1), when the carbon number of the alkyl group is a long chain, the moisture permeability can be further reduced, and among them, those having 6 to 30 carbon atoms are preferable, and those having 10 to 24 carbon atoms are preferred. Particularly preferred. Specific examples thereof include (iso) hexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) stearyl (meth) acrylate, (iso) lauryl acrylate, and the like.

  Examples of the component (d2) include isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and phenoxy (meth) acrylate.

  Examples of the component (d3) include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and hydroxyhexyl (meth) acrylate. Among these, it is more preferable to use hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate to further improve the thixo ratio of the composition itself.

  The blending ratio of the components (d1), (d2), and (d3) is 50 to 500 parts by weight of the component (d2) and 50 to 500 parts by weight of the component (d1) with respect to 100 parts by weight of the component (d3). It is preferable to use 100 parts by weight of component (d2), and particularly preferably 200 to 400 parts by weight of component (d1). By mix | blending in this ratio, the water vapor transmission rate of a resin composition can be reduced significantly.

  When photocuring the composition, (e) a photopolymerization initiator can be used. Specific examples of the component (e) include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide, Ethyl phenyl (2,4,6-trimethylbenzoyl) phosphinate, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane- Examples include, but are not limited to, 1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4 ′-(2-hydroxyethoxy) -2-hydroxy-2-methylpropiophenone, and the like.

  The component (e) needs to be used in an amount of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, particularly preferably 1 to 4% by weight, based on all the ingredients. . By adding at this blending ratio, the composition can be efficiently cured.

  In addition, various additives such as antioxidants, preservatives, antifungal agents, tackifying resins, plasticizers, polymerization inhibitors, antifoaming agents, and wettability adjusting agents are included in the production of the composition according to the present invention. May be.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and demonstrated in detail about this invention, a specific example is shown and it does not specifically limit to these.

<Example 1>
Regarding component (a):
As component (a1), 10 parts by weight of SX15-20 (Asia Industrial Co., Ltd., trade name, polyether skeleton) and SUA-008 (Asia Co., Ltd., trade name, polyether skeleton) 20 parts by weight,
(A2) 10 parts by weight of TE2000 (Nippon Soda Co., Ltd., trade name, polybutadiene skeleton) as a component;
(B) As a component, 10 parts by weight of KE311 (Arakawa Chemical Industries, Ltd., trade name),
(C) As a component, TS720 (Cabosil, trade name, fumed silica) 12 parts by weight,
Regarding component (d):
As a component (d1), LA (lauryl acrylate) 30 parts by weight,
(D2) 20 parts by weight of FA-512AS (Hitachi Chemical Co., Ltd., trade name, dicyclopentenyloxyethyl acrylate) as a component;
(D3) 10 parts by weight of HPMA (hydroxypropyl methacrylate) as a component;
As component (e), 3 parts by weight of irgacure 184 (BASF, trade name),
Were mixed to prepare a photo-curable resin composition of Example 1.

<Examples 2-4, Comparative Examples 1-8>
The photocurable resin composition was produced similarly to Example 1 using the mixing | blending shown to Tables 1-2. The raw materials used in each example are shown below.
The following were used as raw materials related to the component (a).
UN-8030X (Negami Kogyo Co., Ltd., trade name, polyester skeleton)
The following were used as raw materials related to the component (c).
R972 (Evonik, trade name, fumed silica)
The following were used as raw materials related to the component (d).
THF-A (tetrahydrofurfuryl acrylate)
PO-A (phenoxy acrylate)
The following were used as raw materials related to the component (e).
KIP-150 (Lamberti, trade name)

<Evaluation of physical properties of photocurable resin composition>
Viscosity (high speed): Measured according to JIS Z 8803. The measurement was performed with a viscometer (Toki Sangyo Co., Ltd., cone plate viscometer, trade name: RE550R). Moreover, it measured at 3 degrees, R7.7, 10 rpm, a 120 second value, and 25 +/- 1 degreeC as measurement conditions, The said measured value was made into the viscosity (high speed). A viscosity (high speed) of 5000 to 20000 mPa · s is suitable for a gasket.

  Viscosity (low speed): Measured according to JIS Z 8803. The measurement was performed with a viscometer (Toki Sangyo Co., Ltd., cone plate viscometer, trade name: RE550R). Moreover, it measured at 3 degrees, R7.7, 1 rpm, a 120 second value, and 25 +/- 1 degreeC as measurement conditions, The said measured value was made into the viscosity (low speed).

  Thixo ratio: The value obtained by dividing the viscosity (low speed) by the viscosity (high speed) was defined as the thixo ratio (thixo ratio = viscosity (low speed) / viscosity (high speed)). If the thixo ratio is 4 or more, sagging can be prevented and it is suitable for a gasket.

Moisture permeability: Measured according to JIS Z 0208. As measurement conditions, a sample was stored in an environment of 60 ° C./90% RH, and moisture permeability was calculated from the change in weight. A moisture permeability of 130 g / m ² · 24 h or less is suitable for gaskets.

  Compression set: Measurement was performed according to JIS K 6262 except that the size of the test piece was changed. Specifically, a 10 mm × 10 mm × 2 mmt test piece was compressed at 80 ° C. for 16 hours, opened immediately after removal from the test tank, and measured at the time when the temperature returned to room temperature. A compression set of 25% or less is suitable for a gasket.

  About the measurement of the compression set in the comparative examples 3 and 5, the sample broke during the measurement. Further, in Comparative Example 6, the rosin ester as the component (b) was deposited before the viscosity was measured, and could not be measured.

  The evaluation results of Examples and Comparative Examples are also shown in Table 1 and Table 2. In Examples 1 to 4, all evaluation items were within a range suitable for gaskets. On the other hand, Comparative Examples 1 to 8 were not suitable for gaskets in any of the evaluation items.

Claims (5)

(A) 10 to 60% by weight of urethane (meth) acrylate,
(B) 1-35% by weight of rosin ester,
(C) 1-15% by weight of a thixotropic agent,
(D) 20 to 70% by weight of (meth) acrylate monomer,
(E) 0.1-10 wt% of photopolymerization initiator,
And the component (a) is
(A1) urethane (meth) acrylate having a polyether skeleton, and
(A2) urethane (meth) acrylate having a polybutadiene skeleton,
A photocurable resin composition for gaskets, comprising:   2. The photocurable resin composition for gasket according to claim 1, comprising 1 to 80 parts by weight of the component (a2) with respect to 100 parts by weight of the component (a1). The component (d) is
(D1) a (meth) acrylate monomer containing a linear or branched alkyl group as a substituent,
(D2) a (meth) acrylate monomer containing a cyclic alkyl group as a substituent,
(D3) a (meth) acrylate monomer containing a hydroxyl group,
The photocurable resin composition for a gasket according to claim 1, wherein the composition is one or more components selected from the group consisting of:   The component (d2) is contained in an amount of 50 to 500 parts by weight and the component (d1) is contained in an amount of 50 to 500 parts by weight with respect to 100 parts by weight of the component (d3). Photocurable resin composition for gaskets.   The photocurable resin composition for a gasket according to any one of claims 1 to 4, wherein the component (d) does not contain an ether skeleton.