JPH04136912A - Light control liquid crystal sheet - Google Patents

Abstract

PURPOSE:To enhance the adhesive property between a liquid crystal layer and transparent electrode films and to prevent the generation of interlayer peeling by laminating and integrating the transparent electrode films on both the front and rear surfaces of the liquid crystal layer consisting of a photosetting resin into which an acrylic compd. contg. phosphorus and the liquid crystal are incorporated. CONSTITUTION:This light control liquid crystal sheet is formed by laminating and integrating two sheets of the transparent electrode films on both the front and rear surfaces of the liquid crystal layer 1 in such a manner that the respective transparent electrodes 2a, 2a are positioned on the inner side. The liquid crystal layer 1 is a thin layer of about 5 to 50mum thickness consisting of the photosetting resin contg. the acrylic compd. contg. the phosphorus, the liquid crystal, a photoinitiator and microbeads and the liquid crystal is separated in a liquid drop state autogenously by a phase sepn. therein and forms a continuous phase. The acrylic compd. contg. the phosphorus is incorporated in order to improve the adhesive property between the liquid crystal layer 1 and the transparent electrode films 2. Epoxy-contg. methacrylate and acid phosphooxy ethyl methacrylate, etc., are used as the adequate compd. thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a light control liquid crystal sheet that has good adhesion between a liquid crystal layer and transparent electrode films on both sides of the liquid crystal layer.

[Conventional technology]

A conventional general dimming liquid crystal sheet has a structure in which transparent electrode films are laminated and integrated on both upper and lower surfaces of a liquid crystal layer made of a resin containing liquid crystal. When a voltage is applied between the transparent electrodes of the upper and lower transparent electrode films, such a dimming liquid crystal sheet
The liquid crystal molecules in the liquid crystal layer align in the direction of the electric field and change from a light-scattering state (cloudy state) to a light-transmitting state (transparent state).
Various light control applications are expected.

By the way, when manufacturing the above-described light control liquid crystal sheet, a thermosetting resin such as a thermosetting epoxy resin blended with liquid crystal is often used as the resin forming the liquid crystal layer. However, when using such thermosetting resins, it is necessary to incorporate a relatively large heating device such as a heating furnace into the assembly line, and the time required for curing is also increased. Photocurable resins such as photocurable acrylic resins containing liquid crystals have come to be used as resins. When such a photocurable resin is used, it can be rapidly cured using a simple ultraviolet irradiation device, but on the other hand, there are the following problems.

[Problem to be solved by the invention]

That is, when a liquid crystal layer is formed using a photocurable resin containing liquid crystal, the adhesion between the liquid crystal layer and the transparent electrode film becomes worse than when forming a liquid crystal layer using a thermosetting resin containing liquid crystal. In particular, the transparent electrode of the transparent electrode film is crystalline I
If it is made of TO, the adhesion will be significantly reduced. If the adhesion between the liquid crystal layer and the transparent electrode film decreases in this way, delamination may occur when the dimming liquid crystal sheet is folded, rolled and transported, or bonded to glass or plastic plates, resulting in defective products. Furthermore, when trimming the edges of the dimming liquid crystal sheet to provide collector electrodes and terminal pieces, the edges tend to peel off between the eyebrows, resulting in poor workability.

[Means to solve the problem]

In order to solve the above problems, the light control liquid crystal sheet of the present invention has transparent electrode films laminated and integrated on both upper and lower surfaces of a liquid crystal layer made of a photocurable resin containing a phosphorus-containing acrylic compound and liquid crystal. It is characterized by

[For production]

When an acrylic compound containing phosphorus is contained in the photocurable resin of the liquid crystal layer as in the light control liquid crystal sheet of the present invention, the adhesion between the liquid crystal layer and the transparent electrode film is improved by the action of the compound. In particular, when the transparent electrode of the transparent electrode film is made of crystalline ITO, the tensile shear strength and T-peel strength are improved by 4 to 5 times as described below.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the dimming liquid crystal sheet 1 of the present invention. This light control liquid crystal sheet is made by laminating two transparent electrode films 2, 2 on both the upper and lower surfaces of a liquid crystal layer 1 so that the respective transparent electrodes 2a, 2a are on the inside (liquid crystal layer side). One end edge of the sheet is formed by partially cutting off the liquid crystal layer 1 and the lower transparent electrode film 2, and forming the upper transparent electrode 2a.
At the other edge of the sheet, the liquid crystal layer 1 and the upper transparent electrode film 2 are partially removed to expose the lower transparent electrode 2a. And each transparent electrode 2a, 2
Collecting electrodes 3, 3 are formed in a band shape on the exposed part of a, and terminal pieces 4, 4 for connecting the leash cotton are adhered to the collecting electrodes 3, 3 with conductive adhesive, etc., and both ends of the dimming liquid crystal sheet are The edges are covered with insulating tape 5, 5.

The liquid crystal layer 1 described in -F is a thin layer with a thickness of about 5 to 50 μm made of a photocurable resin containing an acrylic compound containing phosphorus, liquid crystal, a photoinitiator, and microbeads, and inside it, the liquid crystal is Due to phase separation, it spontaneously disperses in the form of droplets or forms a continuous phase.

A commercially available acrylic or epoxy photocurable resin is suitable as the photocurable resin, and a commercially available nematic liquid crystal is suitable as the liquid crystal. The proportion of the photocurable resin in the entire liquid crystal layer is desirably about 30 to 90% (weight %, the same applies hereinafter), and the proportion of the liquid crystal is desirably about 10 to 70%. When the proportion of liquid crystal is less than 10%, the degree of cloudiness becomes weaker because the light scattering of the liquid crystal layer when no voltage is applied is insufficient; conversely, when the proportion of liquid crystal is less than 7%,
If it is more than 0%, the adhesion between the liquid crystal layer 1 and the transparent electrode film 2 is likely to be inhibited by a large amount of liquid crystal, making it difficult to fully achieve the object of the present invention.

The phosphorus-containing acrylic compound (hereinafter referred to as phosphorus-containing acrylic compound) is used in the liquid crystal layer 1 and the transparent electrode film 2.
A suitable compound is epoxy-containing phosphorus methacrylate, such as commercially available product name New Frontier S-23A (Daiichi Kogyo Seiyaku ■).
), acid phosphooxyethyl methacrylate,
For example, commercially available product name Bosmer M (manufactured by Unichemical ■) is used. The proportion of this compound in the entire liquid crystal layer is 0.
．． It is desirable that the amount is about 0.01 to 5%, and if it is less than 0.01%, it will be difficult to exhibit a remarkable adhesion improving effect, and if it is more than 5%, the adhesion will not be improved any further.

Furthermore, the microbeads described above serve as spacers to increase the thickness of the liquid crystal layer 1, and microbeads made of transparent resin having an optical refractive index that is the same as or similar to that of the photocurable resin are preferably used. used.

The proportion of the beads in the entire liquid crystal layer is preferably about 0.1 to 5%. Note that Microbiz is not an essential component and may be omitted.

The transparent electrode film 2 laminated on both the upper and lower surfaces of the liquid crystal layer 1 is a transparent resin film (thickness = 5
Crystalline or non-quality +TO on one side (0~200μm)
A transparent electrode 22'' formed by vapor-depositing or sputtering a metal oxide such as tin oxide or tin oxide is used for 67''>1, but gold, palladium, aluminum, etc. Transparent electrodes 2a are formed by vapor deposition or sputtering with metal, transparent conductive bamboo coatings,
C, in which the transparent electrode 2a is formed by coating No. 1, is also good.

The transparent electrode 2a does not necessarily need to be formed on the entire surface of the resin film, and may be formed in a certain design or pattern. If a transparent electrode film in which such a design or pattern-like transparent electrode is formed on either or both of the upper and lower transparent electrode films is used, the patterned light control material becomes transparent in the design or pattern when voltage is applied. can be obtained.

In addition, in order to improve weather resistance and provide various functions, it is of course possible to use a composite transparent electrode film in which a weather resistance improving film, an ultraviolet ray cutting film, a heat ray cutting film, etc. are laminated. Further, the collector electrode 3 is for suppressing the voltage drop of the transparent electrodes 2a, 2a, and is formed by applying a conductive paste or pasting a metal foil tape to the exposed edges of the transparent electrodes 2a, 2a. There is.

When manufacturing a light control liquid crystal sheet with the following configuration, first, a phosphorus-containing acrylic compound, liquid crystal, a photoinitiator, and microbeads are mixed into a photocurable resin to form a mixture for forming a liquid crystal layer. Adjust and apply the mixture to earthwork transparent electrode film 2
．． 2 to form a layer with a thickness of about 5 to 50 μm, and both sides of the layer are irradiated with light (ultraviolet light). Then, the photocurable resin quickly hardens, and the upper and lower transparent electrode films 2 are cured by the action of the phosphorus-containing acrylic compound contained in the resin.
, 2 and the transparent electrodes 2a, 2a are formed. Next, in the l/rimming step, one edge of the transparent electrode film 2 on the -1- side and the lower transparent electrode film 2 are removed.
Cut off the other edge, form the aforementioned father electrode 3.3 on the exposed portion of the upper and lower transparent electrodes 2a, 2a, attach the terminal piece 4 for connecting the lead wire, and cover both edges with insulating tape 5. do. This trimming work is performed on the liquid crystal layer 1 and the transparent electrode film 2.
, 2, it can be performed with high efficiency, and there is almost no risk of peeling between the eyebrows during the work.

The light control liquid crystal sheet of the present invention obtained in this manner is attached to a place where light control is to be performed, either alone or by bonding it to a transparent substrate such as a glass plate or a plastic plate, and the terminal piece 4 has a υ = nide. Connected.

When a voltage is applied between the upper and lower transparent electrodes 2a, 2a, the liquid crystal molecules in the liquid crystal layer 1 are oriented in the direction of the electric field from a random state, and the liquid crystal layer 1 becomes transparent.When no voltage is applied, the liquid crystal molecules in the liquid crystal layer 1 become transparent. The molecules become randomly oriented again and form the liquid crystal layer.
becomes cloudy and exhibits a dimming function.

Next, a test conducted to evaluate the adhesion performance of the light control liquid crystal sheet of the present invention will be described.

[Test 1: Tensile shear strength] A liquid crystal layer forming mixture having the composition shown in Table 1 below was prepared,
By sandwiching the above mixture between two transparent electrode films (A-125 manufactured by Kijin ■) on which transparent electrodes of crystalline ITO are formed and irradiating the mixture with ultraviolet rays, a structure as shown in Figure 2 (a) is obtained. A test piece A for a tensile shear test in which a transparent electrode film 2.2 was laminated via a liquid crystal 1-J1 having a thickness of about 20 μm was prepared based on JIS K68505.2.

Incidentally, the ultraviolet ray irradiation was carried out from both sides under the conditions of an ultraviolet intensity of 2 mW/cm 2 and an irradiation time of 1 minute.

Next, non-quality ITO was used instead of the transparent electrode film.
Test piece B was prepared in the same manner as described above, except that a transparent electrode film (B500.-123 manufactured by Kijin Ohsuke Co., Ltd.) on which a transparent electrode was formed was used.

Table 1 Table 2 For comparison, a mixture for forming a liquid crystal layer that does not contain a phosphorus-containing acrylic compound (the composition from which the phosphorus-containing acrylic compound is removed from the composition in Table 1 above) was prepared, and this mixture was Comparative test pieces C and D were prepared in the same manner as above.

JISK tensile shear strength of the above test pieces A, B, C, D
It was measured based on the measurement method of 6850.

The results are shown in Table 2 below. This measurement was performed using Autograph AGS-500 (AI Shimadzu Corporation).
Tensile speed 50mm/min, test temperature and humidity 23℃-50%
This was conducted under RH/24 hour conditions.

(Margins below) From the measurement results shown in Table 2, test pieces A and B of the present invention containing a phosphorous-containing acrylic compound in the liquid crystal layer were found to be more effective than comparative test pieces C and D that did not contain the compound. , the tensile shear strength is significantly improved, especially when the transparent electrode of the transparent electrode film is made of crystalline ITO, as is clear from the comparison between test piece A and test piece C. is about 5
It can be seen that the improvement is doubled. Therefore, even if the light control liquid crystal sheet of the present invention containing a phosphorus-containing acrylic compound in the liquid crystal layer is rolled and bent or bent, there is no need to worry about it peeling off due to its high tensile shear strength. .

[Test 2: T-peel strength] A liquid crystal layer forming mixture having the composition shown in Table 1 above was prepared,
By sandwiching the above mixture between a transparent electrode film (^-123 manufactured by Banjin 41) on which a transparent electrode of crystalline ITO is formed and irradiating it with ultraviolet rays, a product as shown in Figure 2 (b) is obtained. A test piece E for a T-shaped peel test was prepared in which a transparent electrode film 2.2 was laminated with a liquid crystal layer 1 having a thickness of about 20 μm interposed therebetween. Incidentally, the ultraviolet ray irradiation was performed from both sides under the same conditions as in Test 1 above.

Next, non-quality ITO was used instead of the transparent electrode film.
Test piece F was produced in the same manner except that a transparent electrode film (Ondai (Horizontal 8300-125)) on which a transparent electrode was formed was used.

For comparison, a mixture for forming a liquid crystal layer that does not contain a phosphorus-containing acrylic compound (from the composition shown in Table 1 above, excluding the phosphorus-containing acrylic compound) was prepared, and using this mixture, a comparative sample was prepared. Test pieces G and H were prepared respectively.

The T-peel strength of the above test pieces E, F, G, and H was measured using Autograph AGS-500 (No. 11 manufactured by Shimadzu Corporation) at a tensile speed of 200 mm/min. The results are shown in Table 3 below.

Table 3 From the measurement results shown in Table 3, the test pieces E and F of the present invention containing a phosphorus-containing acrylic compound in the liquid crystal layer had the following properties: The T-peel strength is markedly improved, especially when the transparent electrode of the transparent electrode film is made of crystalline 1'Fo, as is clear from the comparison between test piece E and test piece G. It can be seen that the shape peel strength is increased by about 4 times. Therefore, when trimming the ends of the dimming liquid crystal sheet of the present invention containing a phosphorus-containing acrylic compound in the liquid crystal layer, there is no need to worry about peeling off Ml, and the work can be carried out efficiently. It can be performed.

〔Effect of the invention〕

As is clear from the above explanation, the light control liquid crystal sheet of the present invention has excellent adhesion between the liquid crystal layer and the transparent electrode film, so it cannot be transported by being folded or rolled, or bonded to glass or a plastic deck board. When doing so, there is almost no risk of peeling between the eyebrows and resulting in a defective product, and the work of trimming the edges and providing collector electrodes and terminal pieces can also be carried out efficiently.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing one embodiment of the light control liquid crystal sheet of the present invention, and Figures 2 (a) and (b) are perspective views of test pieces exploded to measure tensile shear strength and T-peel strength, respectively. It is a diagram. DESCRIPTION OF SYMBOLS 1...Liquid crystal layer, 2...Transparent electrode film, 2a...Transparent electrode, 3...Collector electrode, 4...Terminal piece, 5...Insulating tape.

Claims (1)

[Claims] (1) A dimming liquid crystal sheet characterized by integrally laminating transparent electrode films on both upper and lower surfaces of a liquid crystal layer made of a photocurable resin containing an acrylic compound containing phosphorus and liquid crystal.