JPH0697569B2 - Printable dielectric composition - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to novel UV curable printable dielectric compositions, particularly membrane touch switc.
h) to a composition for use in

BACKGROUND OF THE INVENTION Membrane touch switches are normally open, low voltage, pressure sensitive devices that have recently been used in a wide variety of applications including appliances, electronic games, keyboards, and other appliances. This is usually a three-layer sandwich construction in which conductive traces are printed inside the top and bottom layers, separated by spacer sheets.
The pressure applied to the top layer establishes a momentary electrical contact between the top and bottom layers through openings in the spacer sheet. Both flexible and rigid switches are possible. The former is typically printed on a flexible polyester base, while the latter uses a printed circuit board bottom plate.

The ease of design and manufacture allows the cost of a membrane touch switch to be lower than its electromechanical equivalent. Nevertheless, they still have to be made of highly reliable electronic materials and these materials have to be compatible with each other. Many polymeric thick film conductors and dielectrics have been developed for this application because the high cure temperatures of many inks available for cermet applications are not suitable for polymeric substrates. Different chemistries have been used recently for both types of inks, and different manufacturing options are also used.

In practice, many manufacturers first select a conductive ink and then look for a compatible dielectric. The choice is very critical in this application. This is because the dielectric is used both to insulate the conductors to allow crossing and to encapsulate to prevent environmental damage. However, the lack of adequate adhesion of dielectrics to substrates and / or conductive inks has limited the market penetration of many dielectric compositions, especially UV curable dielectric compositions.

The current manufacturing method is that the dielectric is screen printable,
It indicates that it can be thermally cured or UV cured. The faster cure obtained with the latter made it a more cost effective method, and the wide applicability of UV cure equipment made this a practical tool. The dielectric must be compatible with the conductive ink and meet certain performance standards. It should be a flexible, peel resistant film, free of pinholes, and have good adhesion to substrates and conductive inks. Cross-application also requires conductive inks to have good adhesion to the dielectric, often also specifying the adhesion of the dielectric to itself. Electrical requirements call for low dielectric constant, high insulation resistance, and high breakdown voltage. The physical and electrical properties should not deteriorate under various environmental conditions.

In assembled switches, dielectric defects can result in electrical or physical damage to the switch. Both material vendors and switch manufacturers rigorously test parts under fresh and accelerated aging conditions to reduce the probability of their occurrence. Electrical defects mean that a short circuit has occurred due to pinholes, conductive impurities in the formulation, weighting or other dielectric defects in the hair under pressure environmental conditions. Physical defects result from blistering, softening or cracking. Either of these can occur during the manufacturing process or during use.
Blistering can occur due to incompatibility of the dielectric with the conductor or substrate, and humidity sensitivity. Softening can occur under high humidity conditions or in solvents from conductive inks, and cracking can occur due to the inherent brittleness of the cured composition. All of these problems can be prevented with properly formulated inks.

A more difficult problem is the problem of bond loss. Since this is closely related to the substrate, the problem is compounded by the large number of possible substrates. Polyester films are most widely used in touch switches, but polycarbonate and polyimide films are sometimes used. Each film manufacturer typically provides each product of varying performance with different surface properties, with variable treatment methods and / or surface pretreatments. The film is also given a heat treatment to reduce shrinkage in the subsequent curing step.

Different polyester films have different physical surfaces
It For example, Mylar EL 500 and 500D⁽⁷⁾Both poly
The ester film makes the film easier to handle.
The slip pre-treatment shows evidence of a rough surface. on the other hand,
Melinex O⁽⁶⁾The polyester film is very smooth
Has a smooth surface. Mylar 500D polyester fill
Mu is Mylar Much more than ER500 polyester film
It has small particles and gives a transparent appearance, but Mylar EL500
Has a hazy appearance. Melinex O polyester
The film is also very transparent, but it is not easy to handle
However, it has the drawback of sticking to itself. I will be predicted
As such, the adhesion to these surfaces is very variable
And is not directly related to surface smoothness. Melinex O poly
Ester films generally exhibit the lowest shape. Membrane
Itch manufacturers often say that cost,
Since the substrate is chosen for its stability and appearance,
Physical surface properties are often overlooked and in terms of adhesion
It can be critical to the performance of the ink.

SUMMARY OF THE INVENTION Accordingly, the present invention is first directed to an improved screeny printable dielectric composition having good adhesion to a wide range of substrates, the printable dielectric composition comprising: ) 25-35% by weight of finely divided particles of an inorganic adhesion agent selected from talc, mica and mixtures thereof, and (b) 75-65% by weight UV curable liquid composition (1) 20-50% by weight of acrylated rubber-modified epoxy resin oligomer
sin oligomer), (2) 5-25 wt% acrylated polydiene oligomer, and (3) 35-75 wt% alkyl acrylate.

The invention, in a second aspect, is directed to a membrane touch switch comprising upper and lower flexible layers having opposed conductive regions separated by an adhesive spacer layer of the above composition.

The invention, in yet another aspect, comprises upper and lower flexible layers having opposed conductive regions separated by adhesive spacer layers and conductive traces extending therefrom and encapsulated within the layers of the composition. Is intended for membrane touch switches.

In yet another aspect, the invention is directed to a membrane touch switch comprising upper and lower flexible layers, at least one layer having a plurality of intersecting electrically conductive regions separated from each other by layers of the composition. ing.

Adhesion Test The most accepted standard for measuring the adhesion of membrane switch materials is the tape test described in the literature (ASTM D3359-78, Method B). For films less than 5 mils thick, through the ink cured on the substrate surface (th
10 x 10 with a sharp cutting tool
It is necessary to form a (10by10) lattice pattern. The instrument for this purpose is the Gardner / Neotec Instrument Divison of
You can get it from Pacific Scientific. A pressure sensitive tape (eg 3M Scotch ⁽¹⁰⁾ Brand 810) is applied over the grid pattern and removed in a continuous, sharp, pullless motion. Adhesiveness is from OB to 5B depending on the degree of ink removal
Indicated by the grade. The highest grade shows no ink removal.

Many inks that fail this crosshatch test, however, show acceptable adhesion in a simple tape pull test. This indicates that the adhesion loss is due to exfoliation of the ink from the substrate due to the excess energy imparted to the ink during the cutting operation. If this energy cannot be stopped from lateral movement across the ink surface interface, these inks will give poor crosshatch adhesion. It is often observed that inks with a nominal crosshatch bond will pass or fail depending on the type of cut pattern. A few cuts with wide spacing give less energy than several close cuts on the same unit area. The above ASTM test is designed to enhance the reproducibility of the crosshatch test by quantifying the transverse force applied at any particular condition.

PRIOR ART Polymer inks must be strong to retain cross-hatching pressure so that the applied force is absorbed or dissipated in the vicinity of the cut and prevented from moving to the ink surface interface. I have to. One way to do this is to increase the degree of cross-linking. However, this technique is counterproductive in that the resulting composition becomes too brittle for touch switch inks. Another method is to rubber reinforced the composition with an elastomeric inclusion. It is a widely used technique in epoxy chemistry. The third method is to use rigid packed particles such as alumina, silica, and glass spheres. A recently reported study combines these latter two methods in epoxy systems to give hybrid-particle composites. In these systems, dispersed rubber particles enhance the degree of localized plastic shear deformation around the debris, while rigid particles crack-pin.
ning) mechanism to increase crack resistance.

In a research rubber reinforced UV curable dielectric composition
Preliminary work of showed that it has a rough surface eg
Mylar Excellent black for EL500 polyester film
Has a hatch bond, but has a smoother surface such as Meli
nex Not for O polyester film
And. This is the surface area that fits the dielectric in the former case
Is larger and requires extra force for peeling
Can be explained by It contains rigid filling particles
Similar compositions that do not contain a rubber filler are
Cross-hatch for both kana polyester film
Chi adhesion is poor. On the other hand as a hybrid-particle composite
The formulated dielectric is made up of plastic films with varying surface areas.
For a wide variety of substrates including the range of rum (gamut)
Has been found to have good crosshatch adhesion
It This improved adhesive rubber reinforcement mechanism and filler distribution
It is caused by both of the joints. Rigid packing particles
Much smaller contribution to strength (and thus adhesion)
But it has been found that none. Elastomeric inclusions
A similar composition containing no very low crosshatch adhesion
Because it is.

DETAILED DESCRIPTION OF THE INVENTION The present invention is therefore directed to a novel UV curable dielectric composition containing both elastomeric and rigid fill, which has excellent adhesion to a wide range of polyester surfaces.

Such elastomeric fillers can be added to the dielectric composition in various ways. For example, micron-sized core-shell polymers such as those disclosed in US Pat. No. 3,313,748 (Burk) can be incorporated into the dielectric. Another method is to mix an elastomeric polymer such as polyisoprene into the formulation. Both of these technical methods are somewhat effective, but the most effective technique is to choose monomers and oligomers that contribute to both the elastomeric and non-elastomeric properties of the final composition.

Thus, according to the present invention, the rubber fill is incorporated into the composition both by acrylated rubber modified epoxy resin oligomers and by acrylated polybutadiene oligomers. The rheology of the system is adjusted by the use of alkyl acrylates. Mixtures of mono- and difunctional acrylic acrylates are especially preferred for this purpose. Interestingly, the prior art has shown that a wide variety of filler materials work effectively, but the composition of fillers that can be used in the present invention has been found to be very critical. It was It has been found that talc and mica alone are effective for obtaining the high adhesion provided by the composition of the present invention.

A. Inorganic Adhesives A wide range of inorganic fillers were tested for use as adhesives in the compositions of the present invention (see Examples 3-14). However, the only materials generally found to be effective are talc and mica.

The purity of talc and mica does not appear to be critical and the usual commercial qualities of these materials are satisfactory for use in the present invention. Unlike talc which has a single theoretical chemical composition _{(3MgO · 4SiO 2 · H 2} O), mica occurs as several different forms of aluminum silicate, of which muscovite and phlogopite somewhat have commercial usage. Any of these are suitable for use in the present invention. Mixtures of talc and mica can be used without any disadvantages.

At least 25% by weight of talc and / or mica is necessary to obtain the desired level of adhesion of the composition of the present invention. However, about 35% by weight of these adhesives is undesirable in that the cured composition becomes too flexible and dull.

The talc and mica used according to the invention can be treated with silane coupling agents to effect the adhesion of these fillers to the organic polymer component of the liquid curable component. This mainly improves the aging properties of the composition, especially under environmental pressure conditions.

A typical silane coupling agent has the following structure.

R-Si- (OR ') _{3 In the} formula, R is an organic functional group that reacts with an organic polymer,
OR 'is hydrolyzed and condensed with the Si-OH group of the substrate to form Si.
It is a hydrolyzable group which becomes R-Si- (OH) ₃ which gives an -O-Si bond. Various silanes contain different types of organic functional groups. Possible silane coupling agents include amino functional silanes, methacrylate functional cationic silanes, polyamino functional silanes, mercapto functional silanes, vinyl functional silanes and chloroalkyl functional silanes.

B. Epoxy resin oligomer Epoxy resin is a polymer substance having at least one α-epoxy group at the end of the molecular chain or in the molecular chain, and the epoxy resin oligomer generally has a molecular weight of 5,
Refers to 000 or less. The epoxy resin oligomer used in the present invention is as described above.

The main component of the curable liquid component of the present invention and the first rubber material are acrylates of rubber-modified epoxy resin oligomers. These materials can be prepared by reacting the epoxide portion of the polyoxide with the acid portion of a liquid carboxy terminated homopolymer or copolymer of unsaturated monocarboxylic acid and conjugated diene. The manufacture of these materials is described in US Pat. No. 3,892,819 (Naj
var) and US Pat. No. 3,928,491 (Waters). A preferred oligomeric acrylate of this type is the reaction product of a bisphenol A-derived epoxy resin with acrylic acid and a carboxyl-terminated butadiene / acrylonitrile copolymerization. The acrylates of the rubber modified epoxy resin oligomer comprise 20-50% by weight of the curable liquid component, preferably 35-45%.

C. Acrylated Polydiene Oligomer The second essential component of the curable liquid component, and the second rubbery material, is an acrylated polydiene oligomer. These materials are acrylates, usually diacrylates, of low molecular weight liquid conjugated diene oligomers with a molecular weight of 2-4,000. A molecular weight of 3,000 was especially effective. The vinyl content of the oligomers is of the order of 15-30% by weight, with a vinyl content of 20-25% by weight being preferred. Acrylated oligomers of butadiene or isoprene can be used in the present invention.

The polydiene oligomer should be 5-25% by weight of the composition, preferably less than the amount of epoxy resin oligomer is used. 7 to 20% by weight of acrylated polydiene,
Particularly preferred is polybutadiene.

D. Alkyl Acrylate The optional acrylic acrylate constitutes the major part of the curable liquid component of the present invention. In all cases, the alkyl acrylate must be liquid at room temperature. Mono- or polyfunctional acrylates can be used in the present invention. However, the tri- or higher functional acrylate should be no more than 10% by weight of the curable liquid component. It is to prevent excessive crosslinking and shrinkage of the composition. Therefore, mono- and difunctional liquid alkyl acrylates should be present at 35-80% by weight of total curable liquid components.
Preference is given to using. 40-60% by weight is more preferred.

Quite surprisingly, monofunctional acrylates (30-60
%) And a difunctional acrylate (5-20%) mixture was used to obtain better adhesion. More optimal properties include monofunctional and difunctional acrylates at 35-45% by weight and 7.5-15% by weight of the curable liquid component, respectively.
Obtained when accounting for wt%.

Suitable alkyl acrylates include, but are not limited to, the following acrylates and methacrylates.

Acrylate Tetrahydrofurfuryl acrylate Triethylene glycol diacrylate Ethylene glycol diacrylate Polyethylene glycol diacrylate 1,3-butylene glycol diacrylate 1,4-butadiene diol diacrylate Diethylene glycol diacrylate 1,6-hexanediol diacrylate Neopentyl glycol diacrylate 2- (2-ethoxyethoxy) ethyl acrylate tetraethylene glycol diacrylate pentaerythritol tetraacrylate 2-phenoxyethyl acrylate ethoxylated bisphenol A diacrylate trimethylolpropane triacrylate glycidyl acrylate isodecyl acrylate dipentaerythritol monohydroxy Cypenta acrylate Pentaerythritol triacrylate 2- (N, N-diethylamine) ethyl acrylate Hydroxy lower alkyl acrylates such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyhexyl acrylate benzoyloxyalkyl acrylates such as benzoyloxyethyl acrylate and benzoyloxyhexyl acrylate Cyclohexyl acrylate n-hexyl acrylate Dicyclopentenyl acrylate N-vinyl-2-pyrrolidone Isobornyl acrylate Isooctyl acrylate n-lauryl acrylate 2-butoxyethyl acrylate 2-ethylhexyl acrylate 2,2-methyl- (1,3-dioxolan-4-yl ) Methyla For Relate monofunctional acrylates, they are preferred in therefore less volatile of a higher molecular weight. As can be seen from the above list, the alkyl portion of the acrylate is saturated with virtually inert organic groups so long as the resulting acrylate is liquid at room temperature and miscible in the acrylated polydiene oligomer. A preferred alkyl acrylate combination is dicyclopentenyloxyethyl acrylate and tripropylene glycol diacrylate (see Examples 1 and 2).

E. Additives In addition to the main ingredients described above, the composition of the present invention may include various second materials, such as
Elastomeric polymers, initiators that make the composition UV-curable, dyes (soluble or insoluble), and various printing aids such as lev-eling agents, antifoam agents, and thickeners. -ner) may be included.
These materials are known in the art and do not form the basis for the nonobviousness of the present invention.

F. Formulation The composition of the present invention is not difficult to formulate in that simple low energy mixing is sufficient to facilitate dissolution. While it is necessary for the compositions to form stable mixtures, the compositions need not be completely soluble in one another.
In fact, microscopic phase separation during UV curing of these mixtures and thus immiscibility leading to a multi-phase structure was expected.

G. Test Method The polyester film substrate used for the adhesion test is a commercially available 5 mil thick (127 μm) film. The various qualities evaluated are specified in the examples. The polyimide substrate is also a commercially available 5 mil (127 μm) thick film with trademark K
Sold by DuPont as apton ⁽³⁾ . Polycarbonate film is a commercially available 5 mil thick (12
7 μm) (Lexan trademark of General Electric Company)
⁽⁴⁾ ). The polymeric silver conductive ink is commercially available from DuPont as Product 5007.

1 square inch print is 280 mesh stainless steel
Made through a screen, 1.1 mil (25.4 to 27.9μ
m) A test pattern of thickness was obtained. Adhesion test for silver
Exam is Mylar Pre-cured on EL500 polyester film
Made on a 5007 silver conductor. This 5007 is 280 me
Printed on a smart stainless steel screen, 120
It was cured at ℃ for 10 minutes. The printing thickness of silver is 0.5 to 0.7
(12.7 to 17.8 μm).

The adhesion test results reported are from ASTM D3359-78 (Metho
Figure 4 shows the crosshatch adhesive run according to dB). There an 11-cut grid pattern was formed in the dielectric to the substrate in each direction, a pressure sensitive tape was applied on the grid, removed and the adhesion was compared according to the extent of removal by the units below.

The edges of the 5B cut are perfectly smooth. None of the squares in the grid are separated.

Pieces of 4B coating peel off at the intersection. Less than 5% of the area is damaged.

Pieces of 3B coating peel off along the edges and at the intersection of the cuts. The damaged area is 5 to 15% of the grid.

The 2B coating strips along the edges and on the squares. The damaged area is 15 to 35% of the grid.

The 1B coating strips as a large ribbon along the edges of the cut. The whole square peels off. The area damaged is 35 to 65% of the grid.

0B Fragmentation and peeling is worse than 1B. All adhesion tests
3/4 inch wide 3M Scotch Use tape # 810 to
rdner / Neotec Instrument Division of Pacific Scient
With ific's Cross Hatcn Cutter, a medium blade (1.5mm)
11 teeth apart).

All dielectric prints are available in equipment (RPC Industries QC
⁽⁸⁾ Processor Model 1202 AN, two 200W / linea
40 inches / minute (20.3 cm / sec) under ultraviolet light of r inch (79 W / linear cm) medium pressure mercury vapor light bulb)
I cured it. The sample was cured from the lamp in air approximately 3 inches.

Examples Two initial compositions according to the present invention were formulated using talc and mica respectively as a rigid filled adhesive. And an additional 12 compositions were produced. Where,
Other known rigid fillers were used in place of mica and talc. A list of the rigid fillers used in the 20 examples is given in Table I and the adhesion of each formulation is given in Table II.

In Examples 15-20, several adhesive compositions were formulated to exhibit different criticality with respect to liquid components. Finally, in Example 21, a composition similar to that of Example 1 was formulated except that the rigid filler was omitted altogether.

Adhesion data for all 20 examples using a wide variety of substrates are shown in Table II.

Example 1 Table 1 Example No. Adhesive Candidate 1 Talc 2 Mica 3 Sodium-A-Zeolite 4 Hydrated silicate clay 5 Titanium dioxide 6 Alumina 7 Calcium carbonate 8 Trihydrated alumina 9 Trimethylolpropane triacrylate microgel 10 Silica, low crystal, natural microcrystalline “amorphous” 11 Silica, amorphous-fumed 12 Silica, low crystal, natural microcrystalline Novacrite 13 silica, diatomaceous earth 14 silica, silica gel 15-20 talc 21 Control, no adhesive 22 talc 23 Talc 24 Talc UV curable mixture, 26.09 wt% acrylate of rubber modified epoxy resin, 7.34 wt% acrylated polybutadiene oligomer, 26.22 wt% dicyclopentenyloxyethyl acrylate, 6.52 wt% Tripropylene glycol di Acrylate, 0.17
Predispersion (20:80) of wt% copper phthalocyanine dye in trimethylolpropane triacrylate,
Made from 2.44 wt% 2-hydroxy-2-methyl-1-phenyl-1-propanone, 0.69 wt% 2,2-diethoxyacetophenone, 0.53 wt% silicone printing aid, and 30.0 wt% talc. .

After printing and curing, this composition provided excellent crosshatch adhesion on a wide range of substrates, as shown in Table II.

Example 2 Example 1 was repeated except that mica was used instead of talc. After printing and curing, this composition also
As shown in Table II, excellent adhesion was exhibited in a wide range of substrates.

Example 3-14 Example 1 was repeated except that the talc was changed to another filling candidate, as shown in Table II. These compositions did not show excellent adhesion on the wide range of substrates shown in Examples 1 and 2 using talc and mica.

Example 15 Example 1 was repeated except that the acrylate of the rubber-modified epoxy resin was changed to the acrylated epoxy resin. This composition does not exhibit excellent adhesion to the wide range of substrates demonstrated by Example 1.

Example 16 Example 1 was repeated except that the acrylate of the rubber-modified epoxy resin was changed to the acrylated aromatic urethane resin. This composition does not exhibit excellent adhesion to the wide range of substrates shown in Example 1.

Example 17 Example 1 was repeated in the same manner except that an equal amount of acrylated polybutadiene oligomer was replaced with tripropylene glycol diacrylate. This composition does not exhibit excellent adhesion to the wide range of substrates shown in Example 1.

Example 18 Example 1 was repeated except that both the acrylated polybutadiene oligomer and the dicyclopentenyloxyethyl acrylate were replaced with equal amounts of tripropylene glycol diacrylate. This composition does not exhibit excellent adhesion to the wide range of substrates shown in Example 1.

Example 19 Example 1 was repeated except that the dicyclopentenyloxyethyl acrylate was replaced with an equal amount of tripropylene glycol diacrylate. This composition does not exhibit excellent adhesion to the wide range of substrates shown in Example 1.

Example 20 Example 1 was repeated except that both the acrylated polybutadiene oligomer and the tripropylene glycol diacrylate were replaced with equivalent amounts of dicyclopentenyloxyethyl acrylate. This composition does not exhibit excellent adhesion to the wide range of substrates shown in Example 1.

Example 21 Example 1 was repeated except that talc was omitted from the composition. This composition does not show excellent adhesion to a wide range of substrates as the corresponding talc-containing compositions of Examples 1 and 2 showed.

Example 22 A UV curable mixture was prepared by adding 13.30% by weight of an acrylate of rubber modified epoxy resin, 13.23% by weight of acrylated polybutanediene oligomer, 36.33% by weight of dicyclopentenyloxyethyl acrylate, 3.31% by weight of tripropylene glycol Diacrylate, 0.17% by weight
Predispersion (20:80) of copper phthalocyanine dye in trimethylolpropane triacrylate, 2.44% by weight of 2-hydroxy-2-methyl-1-phenyl-1.
-Propanone, 0.69 wt% 2,2-diethoxyacetophenone, 0.53 wt% silicone printing aid, and 30.0
Made from wt% talc. After printing and curing,
This composition gave excellent crosshatch adhesion on a wide range of substrates, as shown in Table II.

Example 23 A UV curable mixture was prepared by using 38.94 wt% acrylated rubber modified epoxy resin, 3.31 wt% acrylated polybutadiene oligomer, 14.23 wt% dicyclopentenyloxyethyl acrylate, 9.73 wt% tripropylene glycol diester. Acrylate, 0.17% by weight
Predispersion (20:80) of copper phthalocyanine dye in trimethylolpropane triacrylate, 2.44% by weight of 2-hydroxy-2-methyl-1-phenyl-1.
-Propanone, 0.69 wt% 2,2-diethoxyacetophenone, 0.53 wt% silicone printing aid, and 30.0
Made from wt% talc. After printing and curing,
This composition gave excellent crosshatch adhesion on a wide range of substrates, as shown in Table II.

Example 24 A UV curable mixture was prepared by adding 38.94% by weight of an acrylate of rubber modified epoxy resin, 3.31% by weight of acrylated polybutadiene oligomer, 10.72% by weight of dicyclopentenyloxyethyl acrylate, 13.23% by weight of tripropylene glycol diacrylate. , 0.17% by weight
Predispersion (20:80) of copper phthalocyanine dye in trimethylolpropane triacrylate, 2.44% by weight of 2-hydroxy-2-methyl-1-phenyl-1.
-Propanone, 0.69 wt% 2,2-diethoxyacetophenone, 0.53 wt% silicone printing aid, and 30.0
Made from wt% talc. After printing and curing,
This composition gave excellent crosshatch adhesion on a wide range of substrates, as shown in Table II.

Trademark (1) Chemlink 5000 is an acrylated butadiene resin
Oligomer trademark (Sartomer Company, West Chester.P
A).

(2) Hycar Is a trademark of carboxy-terminated liquid polymer
(B.F.Goodrich Chemicals.Inc., Akron.OH).

(3) Kapton Is a trademark (E.I.
du Pont de Nemours and Company.Wilmington.DE).

(4) Lexan Is a trademark of polycarbonate film
(General Electric CO..Schenectady.NY).

(5) Luminar Is a trademark of polyester film (T
oray Industries.Inc., Tokyo.Japan).

(6) Malinex Is a trademark of polyester film (I
CI Americas. Inc.).

(7) Mylar Is a trademark of polyester film (E.
I.du Pont de Nemours and Company.Wilmington, DE).

(8) QC is a trademark of the UV light curing device (RPC Indu
stries.Inc..Plainfild.IL).

(9) 5007 is a display of conductive silver conductive ink (EI
du Pont ed Nemours and Company.Wilmgton.DE).

(10) Scotc Is a trademark of Pressure Sensitive Adhesive Tape (3M Corpor
ation.Mlnneapolis.MN).

Claims (10)

[Claims] 1. Finely divided particles of (a) 25-35% by weight of an inorganic adhesive selected from talc, mica and mixtures thereof, and (b) 75-65% by weight curable A liquid composition comprising: (i) 20-50 wt% acrylated rubber-modified epoxy resin oligomer, (ii) 5-25 wt% acrylated polydiene oligomer, and (iii) 35-75 wt% A curable liquid composition comprising an alkyl acrylate, a printable dielectric composition comprising: 2. Finely divided particles of inorganic adhesive selected from (a) 25-35% by weight of talc, mica and mixtures thereof, and (b) 75-65% by weight curable A liquid composition comprising: (i) 20-50 wt% acrylated rubber-modified epoxy resin oligomer, (ii) 5-25 wt% acrylated polydiene oligomer, (iii) 30-60 wt% Functional alkyl acrylate,
And (iv) a curable liquid composition comprising 5-15% by weight of a bifunctional alkyl acrylate, a printable dielectric composition comprising: 3. The proportion of the components of the curable liquid composition is (i) 35-45% by weight, (ii) 7.5-15% by weight, (iii) 35-45% by weight, and (iv) 7.5- The printable dielectric composition of claim 2 which is 15% by weight. 4. A printable dielectric composition according to claim 1 containing up to 5% by weight of an inert dye. 5. UV curable, 0.1-10% by weight
A printable dielectric composition according to claim 1 containing the UV cure initiator of claim 1. 6. The printable dielectric composition according to claim 1, wherein the inorganic particles are subjected to a silane coupling treatment. 7. A printable dielectric composition according to claim 1 containing 0.1-2.0% by weight of printing aids. 8. Finely divided particles of (a) 25-35% by weight of an inorganic adhesive selected from talc, mica and mixtures thereof, and (b) 75-65% by weight of which are curable. A liquid composition comprising (i) 20-50% by weight of an acrylated product of a rubber-modified epoxy resin oligomer, (ii) 5
A printable dielectric composition comprising: -25% by weight of an acrylated polydiene oligomer, and (iii) a curable liquid composition comprising 35-75% by weight of an alkyl acrylate, separated by an adhesive spacer layer. Membrane touch switch with upper and lower flexible layers having facing dielectric regions. 9. Having opposing conductive regions separated by an adhesive spacer layer, extending from the conductive regions,
(A) 25-35% by weight of finely divided particles of an inorganic adhesive selected from talc, mica and mixtures thereof, and (b) 75-65% by weight of a curable liquid composition. (I) 20-50 wt% acrylated rubber-modified epoxy resin oligomer, (ii) 5-25 wt% acrylated polydiene oligomer, and (iii) 35-7
A curable liquid composition comprising 5% by weight of an alkyl acrylate, a printable dielectric composition comprising: a film touch with upper and lower flexible layers having conductive traces encapsulated within the layer switch. 10. Finely divided inorganic adhesive comprising upper and lower flexible dielectric polymer layers, at least one of which is (a) 25-35% by weight of an inorganic adhesive selected from talc, mica and mixtures thereof. Particles and (b) 75-65% by weight of a curable liquid composition comprising:
A cure capable of including (i) 20-50 wt% acrylated rubber modified epoxy resin oligomer, (ii) 5-25 wt% acrylated polydiene oligomer, and (iii) 35-75 wt% alkyl acrylate. A membrane touch switch having a plurality of cross-conductive regions separated from each other by a printable dielectric composition including a liquid composition.