JP2003064195A - Heat-resistant transparent film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant transparent film having all of good heat resistance, flexibility and transparency, and further to provide a method for producing the film. SOLUTION: This heat-resistant transparent film is obtained by reacting 20-70 mol% of hydroxy groups on the side chains or the terminals of a phenoxy resin having >=5,000 number average molecular weight, with an alicyclic polyisocyanate or an aliphatic polyisocyanate so as to be three-dimensionally cured. The film is obtained by casting a resin composition comprising the phenoxy resin, the polyisocyanate and a solvent so as to form a prescribed thickness, carrying out the first step heating to evaporate the solvent, carrying out the second step heating at a temperature higher than that at the first step heating to react the 20-70 mol% of the hydroxy groups on the side chains or the terminals of the phenoxy resin, with the polyisocyanate, and to three- dimensionally cure the film.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat-resistant transparent film having good heat resistance, flexibility and transparency, and a method for producing the same.

[0002]

2. Description of the Related Art In the electronics industry, there has been a remarkable progress in technological innovation in recent years, and the material technology that supports this is also making great strides.
Regarding the development of polymeric materials, which are also one of the constituent materials, many new or higher-performance polymeric materials have appeared, and their respective steps are being solidified. Now,
Inorganic glass, transparency, isotropic, high hardness, heat resistance, noncombustibility, weather resistance, electrical insulation, low water absorption, low thermal expansion coefficient, etc., can be said to be a very balanced material,
It is one of the important basic materials. However, in recent years, improvement in mass productivity, weight, and impact resistance have been demanded as industrial materials, and so-called polymer glass made of an organic polymer is often used depending on the site. It is also true that there are many problems associated with polymer glasses, and enumerating them, low heat resistance, flammability, birefringence phenomenon, low surface hardness, solvent resistance, chemical resistance,
It has a high coefficient of thermal expansion, gas permeability, and hygroscopicity. There is an urgent need to address these problems as the applications expand, especially in the optoelectronics field.

Among these problems, there are problems related to the essence of organic polymers, and its improvement can be said to be an extremely difficult problem. However, if thermosetting transparent resins appear now, they will be a serious problem. The origin of the development of the present inventors lies in focusing on whether a part can be solved. In the field of spectacle lenses, thermosetting transparent resin is
It should be noted that around 40 years engineers from PPG developed an excellent resin called CR-39 and started manufacturing and selling eyeglass lenses by cast polymerization. This resin is diethylene glycol bisallyl carbonate, and a method in which it is put in a glass mold together with a polymerization catalyst and slowly polymerized in a high temperature region from around 40 ° C to 100 ° C for about 20 hours is adopted. The reason why this CR-39 resin was successful is that the raw material monomer is a low-reactivity allyl group, so that the polymerization rate can be controlled easily, and while the resin exhibits a high curing shrinkage rate of 14%, internal strain due to polymerization This is because the adverse effect caused by is mitigated under mild reaction conditions. Regarding spectacle lenses, many improved versions have been developed since then, centering around the allyl resin system, and have reached the present. Not only allyl resins but also thermosetting resins inevitably undergo a considerable level of curing shrinkage, and the most important issue during molding is how to prevent the adverse effects of internal strain due to curing shrinkage. When manufacturing industrial materials, it goes without saying that the method of manufacturing over a long period of time, which is used for spectacle lenses, is not practical.

As a technique relating to the production of a slightly thick thermosetting resin sheet using a special vinyl compound as a base material, JP-A-8-154557, JP-A-8-187795,
JP-A-8-222366 and JP-A-10-100164 include a series disclosed in these, and these provide good heat resistance, flexibility and a heat resistant transparent film having transparency. I can't.

The present inventors have proposed a thermosetting transparent resin film in which the elongation of a cured product is significantly improved by copolymerizing a specific flexible acrylic acid ester monomer based on an epoxy acrylate resin ( JP 2000-159908
JP-A-2000-313756). However, the glass transition temperature of the thermosetting transparent resin film according to the above technique is as low as 73 ° C. at the highest, and therefore the heat shrinkage at a high temperature, for example, 120 ° C. shows a large value of about 2%, and particularly high accuracy is required. It is not suitable for various uses. Behind this is that the glass transition temperature of the polymer forming the skeleton of the above technology is originally as low as about 100 ° C. As a method of further increasing the glass transition temperature of the thermosetting transparent resin regardless of the glass transition temperature of the skeletal polymer, there is a method of increasing the crosslink density. It has been reported that the glass transition temperature can be improved up to 180 ° C by introducing an unsaturated bond into the side chain of the skeletal polymer and increasing the crosslinking density by using a polyfunctional acrylic compound (Japanese Patent Application No. 2000-252581).
However, in this method, when the glass transition temperature is 110 ° C. or higher, the film lacks flexibility and cracks easily occur when bent.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a heat resistant transparent film having good heat resistance, flexibility and transparency and a method for producing the same.

[0007]

Means for Solving the Problems From the new viewpoint, the present inventors have been working on the development of a heat-resistant transparent film having excellent heat resistance, flexibility and transparency, and have completed the present invention. According to the invention of claim 1, 20 to 70 mol% of the side chain and terminal hydroxyl group of the phenoxy resin having a number average molecular weight of 5000 or more is reacted with an alicyclic polyisocyanate or an aliphatic polyisocyanate and three-dimensionally cured. It is a heat resistant transparent film. A second aspect of the present invention is the heat-resistant transparent film according to the first aspect, wherein the heat-resistant transparent film has a glass transition temperature of 110 to 170 ° C. The invention of claim 3 is the heat-resistant transparent film according to claim 1, wherein the heat-resistant transparent film has a total light transmittance of 87% or more. The invention of claim 4 is the heat-resistant transparent film as set forth in claim 1, wherein the heat-resistant transparent film has solder heat resistance. A fifth aspect of the present invention is the heat-resistant transparent film according to the first aspect, wherein the film thickness is 10 to 300 μm. The invention of claim 6 is the heat-resistant transparent film as claimed in claim 1, wherein the film essentially does not exhibit a birefringence phenomenon. In the invention of claim 7, a resin composition containing a phenoxy resin having a number average molecular weight of 5000 or more, an alicyclic polyisocyanate or an aliphatic polyisocyanate, and a solvent is cast to a predetermined thickness, and the first step Heating to volatilize the solvent,
Then, a second stage heating at a higher temperature than the first stage heating is performed to reduce the side chain and terminal hydroxyl group of the phenoxy resin to 20%.
It is a method for producing a heat-resistant transparent film, which comprises reacting ˜70 mol% with the alicyclic polyisocyanate or aliphatic polyisocyanate and three-dimensionally curing. The invention according to claim 8 is the method for producing a heat-resistant transparent film according to claim 7, wherein the solvent used is methyl ethyl ketone. The invention according to claim 9 is the method for producing a heat-resistant transparent film according to claim 7, characterized in that the second stage heating is performed at a temperature of 110 to 180 ° C.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The phenoxy resin used as the base resin used in the present invention has a number average molecular weight of 5,000.
The above is preferable, and when the molecular weight is less than 5,000, the flexibility of the final film becomes unsatisfactory.

Further, in the present invention, it is preferable that 20 to 70 mol% of the hydroxyl groups at the side chains and terminals of the phenoxy resin are reacted with an alicyclic polyisocyanate or an aliphatic polyisocyanate to form a three-dimensional crosslinked structure, When it is less than 20 mol%, the heat resistance which is the object of the present invention is poor, and when it exceeds 70 mol%, a problem occurs in the flexibility which is the object of the present invention.

Examples of the polyfunctional alicyclic or aliphatic polyisocyanate used in the present invention include the following. Hexamethylene diisocyanate, isophorone diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated meta-xylene diisocyanate,
Lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, lysine ester triisocyanate, 1,6,
11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, trimethylhexamethylene diisocyanate.

The glass transition temperature of the heat-resistant transparent film of the present invention is preferably 110 to 170 ° C., and the film having a temperature of less than 110 ° C. has poor heat resistance. For example, the heat shrinkage ratio at 120 ° C. is generally required in the field of optoelectronics. The characteristics to be deteriorated become poor. Further, a film having a glass transition temperature of higher than 170 ° C. has poor flexibility which is the object of the present invention, so that it tends to be broken when folded, for example.

The total light transmittance of the heat-resistant transparent film of the present invention is preferably 87% or more, and when it is less than 87%, the transparency which is the object of the present invention is insufficient. The total light transmittance in the present invention means a value measured based on JIS K7105.

The heat-resistant transparent film of the present invention preferably has solder heat resistance, and general solder bath conditions are 26
It is 0 ° C., and the film may be immersed in this for 1 minute so that no adverse effects such as swelling are observed.

The heat-resistant transparent film of the present invention has a thickness of 10 to
300 μm is preferable, and if it is less than 300 μm, there is a problem in film strength, and if it exceeds 300 μm, it becomes very difficult to volatilize the solvent at the time of producing the film.

The heat-resistant transparent film of the present invention preferably has essentially no birefringence phenomenon. Birefringence phenomenon is X
It can be easily confirmed that there is no difference in the refractive index in the directions of the axes, Y-axis and Z-axis, or by applying polarized light.

The heat-resistant transparent film of the present invention comprises a resin composition containing a phenoxy resin having a number average molecular weight of 5000 or more, an alicyclic polyisocyanate or an aliphatic polyisocyanate, and a solvent at a predetermined thickness. 20% to 70% by mole of the side chain and terminal hydroxyl group of the phenoxy resin by casting on the first stage, heating the first stage to volatilize the solvent, and then performing the second stage heating at a temperature higher than that of the first stage. Can be obtained by reacting with the alicyclic polyisocyanate or aliphatic polyisocyanate and three-dimensionally curing. The heating temperature in the first step is, for example, 40 ° C to 80 ° C, and the heating temperature in the second step is, for example, 110 ° C to 180 ° C. The side chains and terminal hydroxyl groups of the phenoxy resin react quantitatively in almost the same amount as the charged amount of the alicyclic polyisocyanate or the aliphatic polyisocyanate.

As the solvent to be used, various general solvents such as ketone type, ester type and ether type can be used. In particular, methyl ethyl ketone is almost volatilized at the time of the second heating and the solvent remains. It is optimal because it has no harm. If the solvent remains during the second heating, the glass transition temperature does not reach a predetermined high temperature and the heat resistance of the film becomes inadequate. The second stage heating
The same phenomenon as above is observed when the temperature is lower than 110 ° C. If the second heating is performed at a temperature higher than 180 ° C, factors such as thermal discoloration and brittleness are newly introduced, which is not suitable.

In the present invention, various catalysts may be added for the purpose of promoting the reaction between the phenoxy resin and the alicyclic polyisocyanate or the aliphatic polyisocyanate. As the catalyst, amine-based or organometallic-based catalysts are effective, and organotin compounds are particularly preferable.

Since the resin composition of the present invention is restricted to a pot life of about 0.5 hours to 5 hours at room temperature from the time of mixing the alicyclic polyisocyanate or the aliphatic polyisocyanate, it is necessary to prepare a film. It is preferable to utilize equipment for continuously measuring and supplying the main agent (phenoxy resin) and the curing agent (alicyclic polyisocyanate or aliphatic polyisocyanate) as needed. As these facilities, those already known in the industrial process such as polyurethane and silicone resin can be used.

In order to obtain the above-mentioned resin composition, it is desirable that the respective components are mixed as uniformly as possible by using a mixer or the like.
At this time, mixing of air bubbles is unavoidable, but leave it still,
Defoaming is preferably carried out by a method such as heating to lower the viscosity to facilitate the generation of air bubbles, or applying a pressure reduction to forcibly remove air bubbles. There is also an advantage of not having this kind of concern when using the above-mentioned fixed amount supply equipment.

In addition to the above, various additives, for example, ultraviolet absorption, are added to the resin composition for the purpose of improving hardness, adhesiveness, durability, weather resistance, light resistance, water resistance, corrosion resistance and the like. Agent, light stabilizer, light scattering agent, antioxidant, defoaming agent, leveling agent, thixotropy imparting agent, internal release agent, ion scavenger, lubricant, coupling agent, etc. to further improve performance. Can be planned.

[0022]

EXAMPLES The present invention will be further described below with reference to Examples and Comparative Examples. Example 1 The following components were uniformly dissolved and mixed in a flask, and then coated on a polyethylene terephthalate (PET) film in a thickness of 200 μm and dried by hot air at 60 ° C. for 1 minute and 100 ° C. for 5 minutes to remove the solvent. After that, the temperature was further raised to 150 ° C. and kept for 10 minutes to react the hydroxyl group of the phenoxy resin with the polyisocyanate to produce a transparent film. The thickness of the obtained film was 71 μm.

[0023] Phenoxy resin Methyl ethyl ketone solution 100 parts by weight (Phenoxy resin as solids (Phenothote YP-50: number average molecular weight 14500, Cheng Co., Ltd. product) contains 35% by weight) Isophorone diisocyanate 6.84 parts by weight   (Corresponding to 50 mol% of the hydroxyl groups of the phenoxy resin) Dibutyltin dilaurate 0.042 parts by weight

When the physical properties of this film were measured, the following data were obtained. When the film was polarized and tested, no birefringence phenomenon was observed.

Glass transition temperature 138 ° C 180 ° bending test No breakage Solder heat resistance 260 ° C No abnormality after immersion for 1 minute Tensile strength 73MPa Elongation at break 11% Total light transmittance 91% Note) Note that tensile strength and breakage Elongation is JIS K6
It is the value measured based on 911. In the bending test, the film was folded back 180 degrees, and 10 cm ×
After placing a weight of 1 kg on an area of 10 cm for 1 hour,
The state of the folds was observed.

Comparative Example 1 A film was prepared by the same operation and formulation as in Example 1 except that the phenoxy resin in Example 1 had a number average molecular weight of 4500 (Phenototo YD-50: manufactured by Toto Kasei Co., Ltd.). This film was extremely fragile and broke in the 180-degree bending test.

Example 2 A film was prepared in the same manner as in Example 1 except that the compounding amount of isophorone diisocyanate was 3.42 parts by weight (corresponding to 25 mol% of the hydroxyl group of the phenoxy resin). As a result of manufacture, a product excellent in transparency and flexibility was obtained. The physical properties of this film were as follows.

[0028] Glass transition temperature 118 ℃ 180 degree bending test No damage Solder heat resistance 260 ° C No abnormality after immersion for 1 minute Tensile strength 65MPa Elongation at break 14% Total light transmittance 92%

Comparative Example 2 Of the formulations in Example 1, the amount of isophorone diisocyanate was 1.37 parts by weight (10% by weight of the phenoxy resin hydroxyl group).
A film having excellent transparency and flexibility was obtained when a film was produced by the same operation and formulation as in Example 1 except that the amount was equivalent to mol%). However, the glass transition temperature of this film was 106 ° C., which proved to be insufficient for the heat resistance aimed at by the present invention.

Comparative Example 3 A film was prepared in the same manner as in Example 1 except that the amount of isophorone diisocyanate was 10.96 parts by weight (corresponding to 80 mol% of the hydroxyl groups of the phenoxy resin) in the resin mixture in Example 1. Was produced. Although the glass transition temperature of this film was as high as 178 ° C, the flexibility was poor and the film was broken in the 180-degree bending test.

Example 3 In the resin blend of Example 1, hexamethylene diisocyanate was replaced with isophorone diisocyanate 5.18.
A film was prepared by the same operation and formulation as in Example 1 except that the weight part (corresponding to 50 mol% of the hydroxyl group of the phenoxy resin) was used. As a result, a film having excellent transparency and flexibility was obtained. The physical properties of this film were as follows.

[0032] Glass transition temperature 115 ℃ 180 degree bending test No damage Solder heat resistance 260 ° C No abnormality after immersion for 1 minute Tensile strength 48MPa Elongation at break 26% Total light transmittance 89%

COMPARATIVE EXAMPLE 4 The procedure of Example 2 was repeated except that the isophorone diisocyanate was replaced with tolylene diisocyanate.
When a film was produced by the same operation and formulation as in Example 1, a brown film was obtained, which was unsuitable for the purpose of the present invention.

[0034]

According to the present invention, a heat-resistant transparent film having good heat resistance, flexibility and transparency and a method for producing the same are provided.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 75:04 C08L 75:04 F-term (reference) 4F071 AA53 AA78 AA81 AF30Y AF45 BA02 BB02 BC01 BC02 4F205 AA42 AC05 AG01 GA07 GB02 GC06 GE24 GN17 GW06 GW31 4J034 BA03 CA03 DB03 DC02 DG18 HA06 HC03 HC17 HC22 QA02 QC08 QD06

Claims (9)

[Claims] 1. 20 to 70 mol% of a side chain and a terminal hydroxyl group of a phenoxy resin having a number average molecular weight of 5000 or more.
A heat-resistant transparent film obtained by three-dimensionally curing by reacting with an alicyclic polyisocyanate or an aliphatic polyisocyanate. 2. The heat-resistant transparent film according to claim 1, wherein the heat-resistant transparent film has a glass transition temperature of 110 to 170 ° C. 3. The total light transmittance of the heat-resistant transparent film is 8
It is 7% or more, The heat resistant transparent film of Claim 1 characterized by the above-mentioned. 4. The heat resistant transparent film according to claim 1, wherein the heat resistant transparent film has solder heat resistance. 5. The heat-resistant transparent film according to claim 1, wherein the film thickness is 10 to 300 μm. 6. The heat resistant transparent film according to claim 1, wherein the film exhibits essentially no birefringence phenomenon. 7. A resin composition containing a phenoxy resin having a number average molecular weight of 5,000 or more, an alicyclic polyisocyanate or an aliphatic polyisocyanate, and a solvent is cast to a predetermined thickness and heated in the first step. Then, the solvent is volatilized, followed by heating in the second step at a higher temperature than the heating in the first step, and 20 to 70 mol% of the side chain and terminal hydroxyl group of the phenoxy resin is added to the alicyclic polyisocyanate or A method for producing a heat-resistant transparent film, which comprises reacting with an aliphatic polyisocyanate and three-dimensionally curing. 8. The method for producing a heat-resistant transparent film according to claim 7, wherein the solvent used is methyl ethyl ketone. 9. The method for producing a heat-resistant transparent film according to claim 7, wherein the second stage heating is heating at a temperature of 110 to 180 ° C.