JPS63109699A - Composite substance for radiation and ultraviolet curing type damping material - Google Patents

Abstract

PURPOSE:To obtain a composite substance which does not increase in elasticity in a low temperature, by mixing highly viscous urethane acrylate with specific monoacrylate. CONSTITUTION:This composite substance is composed of monoacrylate and urethane acrylate as shown by the expression and the contents of the monoacrylate and urethane acrylate in the whole acrylate component are 60-90 wt.% and 10-40 wt.%, respectively. The single functional acrylate shown by the expression can yield a hardened material having high Tandelta even if the acrylate only is used, but, in order to lower the elasticity to a desired range and set the vicosity of this substance to an appropriate level without lowering the Tandelta, the highly viscous urethane acrylate is mixed. Therefore, this substance does not increase in elasticity even in a low temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a damping material composition for speakers, and more specifically, the present invention relates to a damping material composition for speakers, and more specifically, a damping material composition that is rapidly cured by irradiation with radiation or ultraviolet rays, and which exhibits a small increase in elastic modulus at low temperatures. -Regarding an ultraviolet curable damping material composition.

[Prior art]

A speaker damping material is applied to the edge of a speaker cone for the purpose of damping and reinforcing the speaker.

This edge part plays an important role, and the characteristics of the speaker will change depending on the quality of this part.

In other words, if the edges of the paper cone of the speaker were made of paper, the mechanical vibrations transmitted from the center of the paper cone due to the vibrations of the paper cone would be reflected at the edges.
It appears as peaks and dips in the characteristic curve.

In order to improve such poor frequency characteristics and absorb reflected waves at the edges, a speaker damping material is applied to the entire edge or edge of the paper cone.

Conventionally, as damping materials for speakers of this type, materials in which an acrylic polymer is dissolved in an organic solvent such as toluene or acetic acid ester and the solid content is adjusted to about 30 to 60% by weight have been used.

However, since an organic solvent is used, it is necessary to dry it after application, and since it is generally dried at room temperature, it takes a long time to dry, and it also poses a risk of fire, etc., and is harmful to the human body. Due to occupational safety and health issues, there was a desire for a material that was solvent-free and could be dried or hardened in a short period of time.

The present inventors investigated various radiation/ultraviolet curing materials as solvent-free materials that can be cured in a short time, and found that radiation/ultraviolet curing materials that satisfy the characteristics of (11, (2) below) can be used as damping materials for speakers. A mold damping material composition could be obtained.

(Since the damping material composition 11 is intended for damping and reinforcement, the Tan δ (loss coefficient) of the cured material is high,
In addition, it is necessary to have an appropriate elastic modulus. Tan
It is better to have δ as high as possible from low to high temperatures and from low frequency range to high frequency range, and in general, it is 0.7 or more at room temperature and 0.1 or more even at high temperature. is necessary.

(2) A lower modulus of elasticity is desirable, but since it also serves as reinforcement, a modulus of around 10S to 10'dyne/ad is desirable, and generally 10s to 10'dyne/cn at room temperature.
! A certain amount is used. Furthermore, it is necessary to have an appropriate viscosity for coating workability, and generally, the viscosity is 500~
A speed of about 20,000 cps is desired.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a damping material composition for a speaker that can be cured in a short time without using a solvent and has a small increase in elastic modulus at low temperatures. This composition is particularly useful for speaker edges.

[Structure of the invention]

Therefore, the present invention provides the following monoacrylate (I[
r) and the following urethane acrylate (1) or the following urethane acrylate (■), and in the combination of monoacrylate (III) and urethane acrylate (I), monoacrylate (IIf) accounts for 60 to 90% of the total acrylate component. Urethane acrylate in weight% (
I) is 10 to 40% by weight of the total acrylate component;
In the combination of monoacrylate (III) and urethane acrylate (II), the monoacrylate (III) is 30 to 80% by weight of the total acrylate component, and the urethane acrylate (Il) is 20 to 70% by weight. The gist is a radiation/ultraviolet curable damping material composition.

(a) A copolymer of propylene oxide and tetrahydrofuran, which has a molecular weight of 1,500 to 10,000 and has hydroxyl groups at both ends, is reacted with diisocyanate at both ends, and then both hydroxyl groups and acryloyl groups (or methacryloyl groups) are reacted. Urethane acrylate (I) obtained by reacting a compound having

(b) Molecule ffl 1.500-10.000 Both ends of a copolymer of propylene oxide and tetrahydrofuran having hydroxyl groups at both ends are reacted with diisocyanate, and then a compound having only hydroxyl groups and a hydroxyl group and acryloyl Urethane acrylate (■) obtained by reacting compounds having both groups (or methacryloyl groups).

(cl Monoacrylate represented by the following general formula
(In).

Hereinafter, the configuration of the present invention will be explained in detail.

(a) Urethane acrylate (I).

Molecule ffl 1. ．． A copolymer of propylene oxide (hereinafter referred to as PO) and tetrahydrofuran (hereinafter referred to as THF) having a molecular weight of 500 to 10,000 and having hydroxyl groups at both ends (hereinafter referred to as copolymer A), PO/THF
It is preferable that the molar ratio of is 80/20 to 20/80. Further, if the molecular weight is less than 1,500, the elastic modulus will be high, which is preferable, and if it exceeds 10,000, the curing speed will be slow, making it impractical. Those having a molecular weight of about 2,000 to 6,000 are more preferably used.

Instead of this copolymer A, for example, PO alone, ie,
When polypropylene glycol is used, even if it is blended in the same way and a cured product is obtained, only a product with low Tan δ and poor heat aging resistance can be obtained, and the same is true when using THF alone, that is, polytetramethylene glycol. Even if a cured product is obtained by blending it with the above, only a product with a low Tan δ can be obtained.

The diisocyanates reacted with the hydroxyl groups at both ends of this copolymer A include MDI (methylene diisocyanate), hydrogenated MDI, and TDI () lylene diisocyanate).
, isophorone diisocyanate, hexamethylene diisocyanate, etc. are preferably used, and 1
For example, by using dibutyltin dilaurate as a catalyst and reacting at 80°C for about 4 hours, a reactant having isocyanate groups at both ends (urethane modified product)
can be obtained.

Next, the urethane acrylate (I) having acryloyl groups at both ends can be obtained by reacting the urethane modified product with a compound having a hydroxyl group and an acryloyl group (or methacryloyl group).

This reaction can also be almost completed in about 4 hours at 80°C.

The compounds having a hydroxyl group and an acryloyl group (or methacryloyl group) used here include, for example, 2-hydroxyethyl acrylate (or methacrylate),
Examples include, but are not limited to, 2-hydroxy-propyl acrylate (or methacrylate).

Also, acrylate is preferable to methacrylate in terms of curing speed.

(b) Urethane acrylate ([).

The above-mentioned urethane acrylate (I ).

Compounds having only hydroxyl groups, that is, compounds having only hydroxyl groups and no other functional groups, include various alcohols, phenols, etc., but do not react with isocyanate groups and are photosensitive. In the present invention, there is no problem even if there is a functional group that does not react with the polymer, so other functional groups in the present invention refer to isocyanate groups or functional groups that react with light other than hydroxyl groups. Examples include an amino group, a thiol group, an epoxy group, an acryloyl group (or a methacryloyl group), and the like.

(C1 monoacrylate (III).

The monofunctional acrylate represented by the above formula can provide a cured product with a high Tan δ even when used alone. However, the modulus of elasticity of the cured product (3) is quite high, and the viscosity of the uncured product is also very low, so there is a problem in coating workability when used alone.

Therefore, in order to lower the elastic modulus to a preferable range without lowering Tan δ and further provide appropriate viscosity, the highly viscous urethane acrylate I or (2) is mixed in the composition of the present invention.

In the present invention, when (1) and (1) are essential components, (2) is contained in an amount of 60 to 90% by weight of the total acrylate components, and (2) is contained in an amount of 10 to 40% by weight of all acrylate components.

If (2) is less than 10%, the viscosity decreases and the elastic modulus increases, which is not preferable. When it exceeds 40% by weight, the viscosity increases and Tan δ decreases. If (2) is less than 60%, Tan δ decreases. When it exceeds 90%, the viscosity becomes too low and the elastic modulus also becomes high.

When (1) and (2) are essential components, (2) is contained in an amount of 30 to 80% by weight of the total acrylate component, and (2) is contained in an amount of 20 to 70% by weight. Since ■ has a higher Tan δ than ■, it is possible to contain up to 70% of ■.

In the present invention, other acrylates may be mixed in with the above-mentioned I, ① and ②. For example, a small amount of monoacrylate, which has a very low modulus when cured at a low viscosity, can be added to adjust the viscosity or modulus of elasticity. For example, a cured product having an 'rg of not more than room temperature, more preferably not more than 0° C. can be used more effectively.

In addition, thixotropy (
(thi
Curing accelerators, polymerization inhibitors, etc. can also be added as appropriate.

The product obtained by mixing these has a 500 to 200
It is a liquid material with a viscosity of 1,000 cps, and can be applied without mixing an organic solvent or the like.

Further, these can be instantly cured by irradiation with radiation such as an electron beam, but generally, a photoinitiator can be added and cured with ultraviolet rays within 10 seconds.

By using the composition of the present invention, a material with a small increase in elastic modulus at low temperatures can be obtained. That is, it can be effectively used as a damping material for speakers even in winter and in cold regions.

Examples and comparative examples are shown below.

Examples and Comparative Examples After mixing monoacrylate with a photoinitiator and a polymerization inhibitor in the formulation shown in Table 1 below, urethane acrylate was added and thoroughly stirred and mixed to form a radiation/ultraviolet curable damping material composition. I got it. The viscosity of these compositions was measured using a B-type rotational viscometer. These values are shown in Table 1.

These compositions were exposed to an ultraviolet lamp (80 W/cm, IK
- Using a metal halide lamp), ultraviolet rays were irradiated at 50 mW/cJ for 10 seconds to cure the product, and a sheet with a thickness of 2 mm was obtained.

A test piece was cut from this sheet, and Tan δ and elastic modulus were measured using a viscoelasticity measuring device when the frequency was kept constant and the temperature was varied, and when the temperature was kept constant and the frequency was varied.

For comparison, a material currently used as a damping material for speakers, made by dissolving and diluting an acrylic polymer in an organic solvent (toluene) and having a solid content of 40%, was applied and dried for one day and night. (Comparative Example 1) was cut out and its physical properties were measured in the same manner.

Furthermore, the physical properties when the monoacrylate component is represented by the following formula are also described as Comparative Example 2.3.

These results are shown in Table 1.

(Margins below this page) Note: For near acrylate, the weight percent is based on the total acrylate, and for other additives, the total acrylate is 10%.
Weight part display with 0 weight part.

*A Propylene oxide and tetrahydrofuran (PO/TH
Hydrogenated MDI was added to both ends of the copolymer of F (molar ratio) = 50150) using a trace amount of dibutyltin dilaurate.
A urethane acrylate having acryloyl groups at both ends obtained by reacting at 0°C for 4 hours and then reacting 2-hydroxyethyl acrylate at 80°C for 4 hours.

*B Propylene oxide and tetrahydrofuran (PO/T
Hydrogenated MDI was added to both ends of a copolymer of HF (mole ratio) = 50150) using a trace amount of dibutyltin dilaurate.
React at 0°C for 4 hours, then butanol/2-
Urethane acrylate obtained by reacting hydroxyethyl acrylate at a molar ratio of 50,150 at 80°C for 4 hours.

*D CHz=CH-C-0-CzH4-0-C-
Nl(-C<Hg*E l-hydroxycyclohexylbenzophenone.

*F Methoxyhydroquinone.

As is clear from Table 1, it can be seen that the increase in elastic modulus at low temperatures is smaller than in the comparative example.

〔Effect of the invention〕

As explained above, the composition of the present invention has a suitable viscosity even without containing an organic solvent, so it can be applied without mixing an organic solvent, etc., it does not require a long time to dry, and it does not require radiation.・Since it can be cured in a short time using ultraviolet light, etc., it has excellent productivity and solves occupational safety and health problems such as fire hazards and toxicity to the human body. In addition, the cured product of the composition of the present invention has a high Tanδ from low to high temperatures and from low to high frequency ranges, and the increase in elastic modulus is small especially at low temperatures, so it is effective as a damping material for speakers even in winter. can be used.

Claims (1)

[Claims] The following monoacrylate (III) and the following urethane acrylate (I) or the following urethane acrylate (II)
), and in the combination of monoacrylate (III) and urethane acrylate (I), monoacrylate (III) accounts for 60 to 90% by weight of the total acrylate component and urethane acrylate (I) accounts for 10 to 40% by weight of the total acrylate component. %, and in the combination of monoacrylate (III) and urethane acrylate (II), monoacrylate (III) accounts for 30 to 8 of the total acrylate component.
A radiation/ultraviolet curable damping material composition characterized in that urethane acrylate (II) is 0% by weight and 20 to 70% by weight. (a) Diisocyanate is reacted at both ends of a copolymer of propylene oxide and tetrahydrofuran, which has a molecular weight of 1,500 to 10,000 and has hydroxyl groups at both ends, and then the hydroxyl groups and acryloyl groups (or methacryloyl groups) are reacted.
Urethane acrylate (I) obtained by reacting compounds that have both. (b) A copolymer of propylene oxide and tetrahydrofuran having a molecular weight of 1,500 to 10,000 and having hydroxyl groups at both ends is reacted with diisocyanate at both ends, and then a compound having only hydroxyl groups and a hydroxyl group and an acryloyl group (or Urethane acrylate (I
I). (c) Monoacrylate (III
). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [R_1=H_1 CH_3, R_2=C_2H_4,
C_3H_6, R_3 = alkyl group, n = 1, 2, 3]