JPS5920694B2 - hot melt composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot melt composition, particularly a hot melt composition suitable for effectively suppressing unnecessary resonance and vibration of vibrating equipment such as audio equipment.

Conventionally, in the field of audio equipment such as speakers, adhesives or paints with large internal losses have been used to eliminate unnecessary resonance and vibration.

However, most of these conventional adhesives and paints are so-called solvent-type adhesives in which constituent elements are dissolved in organic solvents. For this reason, the solvent evaporates during bonding, painting, etc., resulting in deterioration of the working environment and air pollution, which has become a major problem. The inventors conducted research and development to solve the problems caused by using solvent-based adhesives and paints, and as a result, they solved the above problems by using a hot-melt composition as described below. In addition, we were able to obtain a solvent-free material that not only has the properties required for devices with delicate characteristics such as audio equipment.

Although hot-melt materials have been widely used in the field of adhesives, conventional hot-melt adhesives have not been able to be used for the purpose of absorbing resonance and vibrations as described above.

That is, this is because the flexibility required to absorb vibrations and the large internal loss are contradictory to the characteristics of general adhesives. The solvent-free material used to suppress resonance and vibration is obtained by the composition, composition, and formulation described in detail below.

First, the object to be used will be explained using a subica as an example. FIG. 1 is a sectional view thereof, and FIG. 2 is a diagram for explaining the abnormal resonance. In the speaker shown in Fig. 1, when an audio signal current is passed through the voice coil 2 installed between the magnets 1, an electromagnetic force acts between the two, and the paper cone 3 integrated with the voice coil 2 vibrates, causing the sound to be heard. emits. Although the cone paper 3 is supported by the frame 6 via the damper 4 and the edge 5, due to the speaker design conditions, at a certain frequency, the cone paper and the edge part may be separated as shown in FIG. Reverse resonance may occur. In this case, it is well known that such reverse resonance can be suppressed by applying a special paint, ie, edge paint, to the edge portion. Edge paints must be flexible and have a large internal loss, and must satisfy strict conditions such as transparency depending on the equipment they are used for, so conventionally they are solvent-free. It was difficult. The hot melt composition according to the present invention includes:
It is suitable for the above-mentioned edge paint, and by using this composition, the edge paint can be made solvent-free.

The hot melt composition according to the present invention is characterized by comprising an ethylene-propylene copolymer, a hydrocarbon oligomer, and a plasticizer.

However, it goes without saying that various stabilizers may be added and contained for the purpose of preventing oxidation, preventing aging, or improving weather resistance at high temperatures. The above-mentioned ethylene-propylene copolymer preferably has a low molecular weight, and specifically, a copolymer with a melt index of 3.0 or more at a temperature of 190°C is used according to the measurement method described in ASTM-Dl238. It is preferable.

Although high molecular weight copolymers are flexible, their internal loss is not large enough, so when they are used in speakers, they produce sharp sound pressure waves as shown by the arrows in their frequency response curves as shown in Figure 3. A decline is seen. Specifically, two types of hydrocarbon oligomers are used.

One is a mixture of low molecular weight aliphatic hydrocarbons, commonly referred to as liquid paraffin, and the other is a low polymer of α-olefins. The α-olefin low polymer includes 3 to 2 α-olefins having 4 to 14 carbon atoms.
It is preferable to use a trimer, and those having an average molecular weight of 300 to 1000 are preferable. When the molecular weight of the α-olefin low polymer becomes large, its compatibility with the ethylene-propylene copolymer becomes poor, and sweating occurs on the surface of the composition. Also, if its molecular weight is small,
Steam is generated at high temperatures during kneading or coating,
Otherwise, problems such as oxidation may occur. The composition ratio of the hydrocarbon oligomer is based on 100 parts by weight of the copolymer.
It is 60 to 180 parts by weight. If the proportion of hydrocarbon oligomer is too small, the composition will have poor flexibility and its internal losses will be low. On the other hand, if there is too much of it, problems such as flowing at room temperature will occur. In actual use, the composition can be arbitrarily selected within the above composition range depending on the usage conditions. A hot melt composition with the desired vibration absorption properties can be obtained using a composition consisting of two components: an ethylene-propylene copolymer and a hydrocarbon oligomer, but depending on the purpose of use, ethylene - Inconvenient cases may occur if only the propylene copolymer and oligomer are used. That is, ethylene as mentioned above
Addition of hydrocarbon oligomers to propylene copolymers causes tackiness. Tack increases as temperature increases. For this reason, it is not suitable for use in exposed surfaces, such as in the edge portions of speakers. The inventors have discovered that a plasticizer can be added to prevent stickiness. As such a plasticizer, one or more of adipate-based, sebacate-based, and phthalate-based plasticizers can be used. Some specific examples include di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, O-phosphate plasticizers, such as heptyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, dinonyl phthalate, diisodecyl phthalate, and diundecyl phthalate, are incompatible with the above compositions and are extremely difficult to use. It was difficult. Among the above-mentioned plasticizers, those having a low molecular weight are difficult to evaporate during heating and mixing, and are not particularly desirable from the viewpoint of reliability or practicality.
In addition, di-2-ethylhexyl adipate and di-2-ethylhexyl sebacate phase separate and flow out at temperatures below about 10°C and below about 0°C, so care must be taken in temperature control in actual use. There are some things you have to do. From a practical standpoint, di-2-ethylhexyl phthalate is most recommended. The amount of plasticizer used is more than that for the ethylene-propylene copolymer.
Rather, the ratio to the hydrocarbon oligomer is important;
55 to 12 parts by weight per 100 parts by weight of hydrocarbon oligomer
Preferably, it is 0 parts by weight. More preferably, in the case of di-2-ethylhexyl phthalate, it is 55 to 100 parts by weight. If the amount of plasticizer used is too small relative to the amount of hydrocarbon oligomer, the effect of preventing tackiness will be poor, and if it is too large, the plasticizer will seep out and cause sweating. The hot melt composition having the above composition has a reduced viscosity and exhibits fluidity at high temperatures.

Therefore, the operating temperature is restricted. For applications where restrictions on operating temperature are a problem, colloidal silica may be added. The colloidal silica used for this purpose preferably has a small average primary particle size of 8 to 50 mμ and is used as a thickener for liquids. As can be seen from the particle size, the uniformly dispersed composition is completely transparent and is particularly suitable for applications requiring transparency. As shown in the comparative example below, when the particle size becomes too large, the thickening effect is no longer achieved, transparency is also impaired, and a cloudy state results.
Another major effect of adding colloidal silica is that it allows for higher internal losses without compromising the flexibility of the composition. It is generally known that the addition of inorganic substances increases internal loss, but it also usually reduces flexibility, so the effect of colloidal silica can be said to be unique. An increase in internal loss means an increase in the vibration absorption effect if the amount of the composition used is the same, and if the same absorption effect is required, it means that the amount of the composition used can be reduced. do. Yet another significant effect of the addition of colloidal silica is that plasticizer leaching can be reduced from a composition consisting of an ethylene-propylene copolymer, a hydrocarbon oligomer, and a plasticizer. As mentioned above, when the molecular weight of the hydrocarbon oligomer increases, the oligomer oozes out from the composition, but in a system in which a plasticizer is added to the composition, mainly the plasticizer oozes out. However, by adding colloidal silica, this oozing is considerably suppressed and oligomers with higher molecular weights can be used. The amount of colloidal silica added is 0.2 to 10% by weight, more preferably 1 to 5% by weight based on the entire composition.
Weight%.

If the amount is less than 0.2% by weight, the effect of adding colloidal silica will be poor, and if it is more than 10% by weight, it will be practically difficult to incorporate it, and the viscosity will become too high even at high temperatures. There is a risk that it will become unsuitable for use as a hot melt type.

In actual use, it is desirable to arbitrarily select a composition within the above composition range depending on the usage conditions. Examples of the present invention will be described below.

Example 1 Ethylene-propylene copolymer (Mitsui Petrochemical Co., Ltd. 2)
In a beaker, 100r of α-olefin low polymer (Lion Yushi Co., Ltd., trade name “Lipolube #200”) 120r1 and 80V of di-2-ethylhexyl phthalate were mixed in a beaker at 120 The mixture was maintained at a temperature of 0.degree. C. and thoroughly stirred to obtain a homogeneous composition.

This composition is non-tacky and very soft.
The repulsion rate was 4% as measured by JISK-6371. In order to examine its vibration absorption effect, the above composition was applied in a molten state to the edge portion of a speaker having a diameter of 20 (::m) and made of fabric.

The frequency characteristics of the speaker after coating are as shown by the solid line in FIG. Note that the frequency characteristics of the speaker before application are as shown by the broken line in the same figure. As is clear from the figure, when the composition is applied to the edge portion of the speaker, the abnormal resonance in the frequency range of 1500 Hz or higher, which was observed before application, is suppressed. It can be seen that, together with the edge sealing effect of this composition, a relatively average sound pressure can be obtained over a wide frequency range. Example 2 100 tons of "Tafuma Ip-0080": The "Lipolube #200" 1257 and di-2-ethylhexyl phthalate 751 were sufficiently stirred at a temperature of 1201C to form a uniform composition.

This composition became tacky at temperatures above about 35°C. When 3.0 tons of this composition was applied to the edge portion, the speaker exhibited frequency characteristics as shown by the solid line in FIG. Example 3 The above "Tafuma I P-0080" 1001i7, "Lipolube #40" (α-olefin low polymer, Lion Yushi Co., Ltd. trade name) 100V, and di-2-ethylhexyl phthalate 100y were heated at a temperature of 120°C. The mixture was thoroughly stirred at the bottom to obtain a homogeneous composition.

Although this composition was not sticky, when stored for a long time at room temperature, exudates consisting mainly of di-2-ethylhexyl phthalate were observed on the surface. A speaker whose edge portions were coated with this composition 3.0f exhibited frequency characteristics as shown by the solid line in FIG. Example 4 100y1 of the above "Tafuma I P-0080", 100t1 of the above "Lipolube #200" and 100f of di-2-ethylhexyl adipate were sufficiently stirred at a temperature of 120C to form a uniform composition.

This composition had no stickiness and was very flexible.
A speaker whose edge portions were coated with this composition 3.0y exhibited frequency characteristics as shown by the solid line in FIG. Example 5 The above "Tafuma I P-0080" 1007, the above "Lipolube #200" 807, and di-2-ethylhexyl sebacate 1207 were sufficiently stirred at a temperature of 120°C to form a uniform composition.

This composition also had no stickiness and was very flexible.
A speaker whose edge portions were coated with this composition 3.07 exhibited frequency characteristics as shown by the solid line in FIG. Example 6 "Tafuma I P-0.080" 1007, "Lipolube #70" 1107, di-2-ethylhexyl phthalate 907, and colloidal silica (Nippon Aerosil Co., Ltd. trade name "Aerosil #300") 97 12
After thorough stirring at a temperature of 0°C, the mixture was kept at a temperature of 100°C using a diroller and kneaded for 10 minutes to obtain a uniform composition.

The composition obtained here was colorless and transparent, had no stickiness, and was very flexible. The repulsion rate was 2%.
The frequency characteristics of a speaker in which this composition 3.07 was applied in a molten state to the edge portions are as shown by the solid line in FIG. The frequency characteristics of the speaker before application are as shown by the broken line in the figure. In order to compare the high temperature fluidity of this composition with a composition that does not contain colloidal silica, the above composition and a composition from which only colloidal silica was removed were diluted onto a 60 mesh wire mesh. Apply, 10
Placed in a dryer at 0°C.

The composition without colloidal silica had already penetrated the back side of the wire gauze after 15 minutes, but the composition containing colloidal silica did not penetrate into the back side even after 10 hours. Example 7 In Example 6, Nippon Aerosil Co., Ltd.'s "Aerosil #300" was replaced with "Aerosil #300" by Nippon Aerosil Co., Ltd. as the colloidal silica.
The composition prepared using "Aerosil #0X50" was also colorless and transparent and very flexible.

The repulsion rate of this composition was 2%. 3. This composition.
07The frequency characteristics of the speaker coated on the edge part are as follows:
It was as shown by the solid line in the figure. The above composition was coated on a 60-mesh wire mesh and placed in a dryer at 100'C to check its high-temperature fluidity, and no penetration into the back surface was observed even after 3 hours. Example 8 The above "Tafuma I P-0080" 1007, the above "Lipolube #70" 1107, di-2-ethylhexyl phthalate 907, and the above "Aerosil #200" 37 were mixed and rolled in the same manner as in Example 6. The mixture was kneaded into a uniform composition.

When this composition is applied on a 60 mesh wire mesh,
Even after being left at a temperature of 90° C. for 1 hour, there was almost no penetration into the back surface. Example 9 "Tafuma I P-0080" 1007, "Lipolube #70" 1507, di-2-ethylhexyl phthalate 1007, and "Aerosil #200" 10
．． 57 was mixed and roll kneaded in the same manner as in Example 6 to obtain a uniform composition.

When this composition is applied on a 60 mesh wire mesh,
Even after being left at a temperature of 100° C. for 3 hours, no penetration into the back surface was observed. Comparative Example In Example 6, when fine silica particles (86% of which had a particle size of 1 μm or less) were used instead of colloidal silica, no thickening effect was observed at all, and the viscosity was easily increased to 60°C at a temperature of 100°C. It penetrated to the back side of the mesh wire mesh.

Furthermore, the entire composition became slightly cloudy. that's all,
As is clear from the Examples and Comparative Examples, by adding a plasticizer and further colloidal silica to a composition consisting of an ethylene-propylene copolymer and an α-olefin low polymer, it is possible to improve the tackiness and the ability to withstand high temperatures. This can effectively prevent the viscosity from decreasing.

In the above examples, only examples of use in speakers have been described, but the hot melt composition according to the present invention can be used in any field where vibrations need to be suppressed or absorbed.
For example, it is a material suitable for use in vibration-proofing materials or sound-absorbing materials.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of a cone-type dynamic speaker, Figure 2 is a diagram to explain the abnormal resonance of this speaker, and Figure 3 is a diagram showing the frequency characteristics of a speaker coated with a composition with low internal loss. The curve diagrams shown in FIGS. 4 and 5 are curve diagrams showing the frequency characteristics of a speaker coated with an example of the hot melt composition according to the present invention in comparison with that of a speaker before coating.

Claims (1)

[Scope of Claims] 1. 1 selected from the group of ethylene-propylene copolymers, hydrocarbon oligomers, and adipic acid ester-based, sebacic ester-based, and phthalic ester-based plasticizers.
A hot melt composition comprising at least one species. 2. In claim 1, the ethylene-propylene copolymer is an ethylene-propylene copolymer having a melt index of 3.0 or more at a temperature of 190°C by the measuring method described in ASTM-D1238. A hot melt composition characterized in that it is used. 3. In the description of claim 1 or 2, the hydrocarbon oligomer is α having 4 to 14 carbon atoms.
- A hot-melt composition characterized in that it uses one or more selected from olefin trimers to 23-mers and liquid paraffin. 4. Claim 1, 2 or 3, wherein the hydrocarbon oligomer is ethylene-
60 to 18 parts by weight of propylene copolymer
A hot melt composition characterized in that it contains 0 parts by weight. 5 Claims 1, 2, 3, or 4
2. The hot melt composition according to item 1, wherein di-2-ethylhexyl phthalate is used as the plasticizer. 6 In the statement of claim 5, the above-mentioned G-2
- A hot melt composition characterized in that ethylhexyl phthalate is contained in an amount of 55 to 100 parts by weight based on 100 parts by weight of the hydrocarbon oligomer. 7. A hot product characterized by comprising an ethylene-propylene copolymer, a hydrocarbon oligomer, one or more selected from the group of adipic ester-based, sebacic ester-based, and phthalic ester-based plasticizers, and colloidal silica. Melt composition. 8 In the description of claim 7, the ethylene-propylene copolymer is based on ASTM-D1238
A hot melt composition characterized by using an ethylene-propylene copolymer having a melt index of 3.0 or more at a temperature of 190° C. according to the measurement method described above. 9. In the description of claim 7 or 8, the hydrocarbon oligomer is α having 4 to 14 carbon atoms.
- A hot-melt composition characterized in that it uses one or more selected from olefin trimers to 23-mers and liquid paraffin. 10 Claim 7, 8 or 9, wherein the hydrocarbon oligomer is present in an amount of 60 to 1 part by weight based on 100 parts by weight of the ethylene-propylene copolymer.
80 parts by weight of a hot melt composition. 11. The hot melt composition according to claim 7, 8, 9, or 10, characterized in that di-2-ethylhexyl phthalate is used as the plasticizer. 12. The hot melt composition according to claim 11, wherein the di-2-ethylhexyl phthalate is contained in an amount of 55 to 100 parts by weight based on 100 parts by weight of the hydrocarbon oligomer. . 13 Claims 7, 8, 9, and 10
12. The hot melt composition according to item 11 or 12, wherein the colloidal silica is contained in an amount of 1 to 10% by weight based on the total amount of the composition. 14 Claims 7, 8, 9, and 10
13. The hot melt composition according to item 1, 11, 12, or 13, wherein the colloidal silica has a particle size of 8 to 40 mμ.