JPH08113691A - Resin composition - Google Patents

Abstract

PURPOSE: To obtain a resin composition which causes whitening depending on temperature and exhibits a remarkable change in transparency due to a temperature difference of 20-30 deg.C by blending a thermoplastic resin and a resin having a crosslinked structure so as to provide at least a specified difference between the gradient of the refractive index-temperature curve of the former resin and that of the latter resin in the inner layer. CONSTITUTION: This composition consists of 10-90 pts.wt. thermoplastic resin (A) and 90-10 pts.wt. resin (B) having a crosslinked structure, wherein the difference ΔN between the gradient of the refractive index-temperature curve of the resin A and that of the resin B in at least one inner layer satisfies the relation of the formula (wherein NdA<q> and NdA<p> respectively are the refractive indexes of the resin A at q deg.C and p deg.C; and NdX<q> and NdX<p> respectively are the refractive indexes of the resin B in the inner layer X at q deg.C and p deg.C). As the resin B, the one which comprises a multilayer structure and whose each inner layer is substantially crosslinked, the total of the inner layers accounts for at least 30wt.% and the outermost layer has flowability and good compatibility and transparency when blended with the resin A, is preferably used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having a whitening property in which transparency is reversibly changed by environmental temperature.

[0002]

2. Description of the Related Art Blends of resins having slightly different temperature dependence of refractive index are known. For example, blends of methacrylic or styrene impact-resistant resins are generally transparent at room temperature and have a temperature of 100.degree. It becomes cloudy only after reaching the above temperature, but the degree of clouding is very small at a temperature difference of 20 to 30 ° C. In addition, in the case of blends other than the above, compatibility of resins with each other is usually poor, and no resin composition has been found that can obtain good transparency even when blended.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a resin composition having a whitening property in which the transparency reversibly changes depending on the ambient temperature, and more specifically, it has a good transparency at room temperature.
It becomes white and opaque at 0 to 50 ° C, or vice versa, it is transparent at 40 to 50 ° C but becomes opaque at room temperature.
It is an object of the present invention to provide a resin composition whose transparency reversibly changes with a temperature difference of 20 to 30 ° C.

[0004]

Means for Solving the Problems The present inventors have completed the present invention as a result of earnestly researching a resin composition having a whitening property in which transparency is reversibly changed by environmental temperature. That is, the present invention comprises 10 to 90 parts by weight of the thermoplastic resin A and 10 to 90 parts by weight of the crosslinked resin B.
A resin composition characterized in that the difference (ΔN) between the gradient of the refractive index of the thermoplastic resin A due to temperature and the gradient of the refractive index of at least one inner layer of the crosslinked structure resin B due to temperature satisfies equation (1). Regarding things.

[0005]

[Equation 2]

(However, NdA ^q and NdA ^p are the refractive indices of the thermoplastic resin A at q ° C. and p ° C., respectively, and NdX ^q and NdX ^p are respectively the inner layer X of the crosslinked resin B. (Refers to the refractive index at q ° C. and p ° C.)

Hereinafter, the present invention will be described in detail. In general,
It is possible to obtain transparency by blending two or more kinds of resins, and the conditions are as follows.

If there are two kinds of resins, (1) both resins have different refractive indexes but have good compatibility, and both resins are micro-dispersed, or (2) both resins. Have the same refractive index, but do not melt each other, and one resin becomes a uniform resin layer and is micro-dispersed in the other resin. To obtain better transparency, the outermost layer of the micro-dispersed resin is uniform This is the case where it has good compatibility with the resin layer.

In the case of (1), the transparency is maintained even if the temperature changes, but in the case of (2), since both resins are transparent because they have the same refractive index, both resins are transparent. When the temperature dependence of the refractive index is different, the whitening phenomenon occurs due to the temperature change.

However, the difference in the temperature dependence of the refractive index of the resin is small, and it is general that the whitening phenomenon occurs only after the change of 50 ° C. or more, which satisfies the above conditions and 20 to 3
It is very difficult to find a resin having a whitening property due to a difference of 0 ° C.

The present inventors have paid attention to the above points, and as a result of repeated studies, found a specific combination of resins satisfying the above conditions and having a whitening property at a difference of 20 to 30 ° C. In order to achieve the object of the invention, formula (1)
It was found necessary to satisfy.

The ΔN value is preferably ΔN ≧ 1.
It is 5 × 10 ⁻⁴ / ° C. In the case of ΔN <1 × 10 ⁻⁴ / ° C., the change in transparency becomes extremely small due to the temperature difference of 20 to 30 ° C., which is not preferable.

It should be noted that the difference in the slope of both refractive indices due to temperature (Δ
A large N) means that, for example, the resins blended at 25 ° C. have the same refractive index at 25 ° C. and have good transparency, but at 50 ° C. the resins have large refractive indices. Differently, it means that the light scattering at the interface of the micro-dispersed particles becomes large, resulting in a strong whitening phenomenon.

As the thermoplastic resin A in the present invention,
There is no particular limitation as long as it satisfies the formula (1),
For example, a block unit composed of an aromatic vinyl monomer unit and / or a methacrylic acid alkyl ester monomer unit and a partially or completely hydrogenated isoprene polymer, butadiene polymer, isoprene-butadiene copolymer or the like. It is preferably a block copolymer composed of a block unit.

In the resin composition of the present invention, the ratio of the thermoplastic resin A to the crosslinked resin B must be 10 to 90 parts by weight for the former and 90 to 10 parts by weight for the latter.
When the proportion of the thermoplastic resin is less than 10 parts by weight, the fluidity of the resin composition is deteriorated, so that the moldability is lowered and the change in transparency is reduced, and when it is more than 90 parts by weight, the transparency is increased. Change is significantly reduced, which is not preferable.

The crosslinked resin B in the present invention comprises a multilayer structure having two or more layers and is produced by an emulsion polymerization method.
It is preferable that the inner layers are substantially crosslinked, and the sum of the weights of the inner layers is 30% by weight or more of the crosslinked resin B. Furthermore, it is uniformly dispersed in thermoplastic resin A, but not melt mixed. When the sum of the weights of the inner layers is less than 30% by weight, the change in transparency is small. Further, it is desirable that the outermost layer has fluidity and has good compatibility in the blend with the thermoplastic resin A.
Further, in the blending of the thermoplastic resin A and the crosslinked structure resin B, it is not always necessary to be transparent at room temperature, but when the outermost layer of the crosslinked structure resin B is blended alone with the thermoplastic resin A, it is possible to obtain a wide temperature range. Those having good transparency are preferable.

Specific examples of the crosslinked resin B are as follows. That is, the inner layer has a methyl methacrylate unit of 70 to 99% by weight, an aromatic vinyl monomer unit of 1 to 30% by weight, and another ethylenically unsaturated monomer unit of 0 to 20% by weight which is copolymerizable with these units. Multifunctional crosslinkable monomer unit and / or multifunctional grafting monomer unit 0.1 to 0.1
It is a copolymer composed of 5% by weight, and its outer layer is 70 to 100% by weight of a methyl methacrylate unit, and 0 to 20% by weight of at least one alkyl acrylate unit in which an alkyl group has 1 to 8 carbon atoms. , And other ethylenically unsaturated monomer units copolymerizable therewith, which have an intrinsic viscosity of 0.10 to 0.50 dl / g measured in chloroform at 20 ° C. It is preferably a copolymer.

As a blending method in the resin composition of the present invention, a method of melt mixing in an extruder is generally used in pelletizing, sheeting, filming and the like, but it is not particularly limited.

Further, UV absorbers, lubricants, dyes and pigments which are usually used in the resin composition of the present invention can be added as required.

The injection-molded articles, sheets and films obtained from the resin composition of the present invention have a very remarkable change in transparency due to a temperature difference of 20 to 30 ° C., and can be applied to the intended use. Is.

[0021]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto.
In addition,% and part in each Example represent weight% and weight part, respectively.

Each physical property was determined by the following method. (1) Intrinsic viscosity: A certain concentration of acrylic resin is dissolved in chloroform and an automatic viscometer (Fica France
(Manufactured by the company). (2) Particle diameter: measured with an electron microscope. (3) Total light transmittance / haze: ASTM-D1003
(2 mm thickness) (4) Refractive index: Digital precision refractometer KPR-20 (manufactured by Karnew Optical Co., Ltd.) The thermoplastic resin A used in this example (hereinafter, the thermoplastic resin may be abbreviated as a resin), The crosslinked resin B was produced by the following method. In the resin production example, / represents a copolymer composition and-indicates a block polymer composition.

Production of Resin (A-1) 500 parts of cyclohexane and 14 parts of S-butyllithium were placed in a pressure resistant reactor, heated to 50 ° C., 50 parts of styrene was continuously added dropwise, and then 300 parts of isoprene were continuously added. Then, 50 parts of styrene was continuously charged and polymerized for 10 hours. Then replace the reaction system with hydrogen,
15 kg / c by adding 8 times the diatomaceous earth supported nickel catalyst
The mixture was reacted at 150 ° C. for 10 hours under a hydrogen pressure of m ² . The reaction product was diluted with cyclohexane, the catalyst was filtered off, and the filtrate was concentrated and dried under reduced pressure to obtain Resin (A-1). NMR
It was confirmed to be a styrene-hydrogenated isoprene-styrene ternary block copolymer, and the styrene content was 2
5%. The hydrogenation rate based on the iodine value was 99%. Further, the refractive index (Nd) of the resin (A-1) at 20 ° C.
Is 1.500, and the temperature dependence coefficient of refractive index (ΔNd)
Was −2.93 × 10 ⁻⁴ / ° C.

Production of Resin (A-2) The styrene content was 5 by the same method as for the resin (A-1).
A styrene-hydrogenated isoprene / butadiene (60% / 40%)-styrene ternary block copolymer having a hydrogenation rate of 0% and an iodine value of 97% was obtained. Further, the refractive index (Nd) of the resin (A-2) at 20 ° C. was 1.530, and the temperature dependence coefficient (ΔNd) of the refractive index was −2.32 × 10 ⁻⁴ / ° C.

Production of Resin (A-3) By a method similar to that of Resin (A-1), styrene / methyl methacrylate having a styrene / methyl methacrylate content of 15% / 15% and a hydrogenation rate of 93% according to iodine value. A hydrogenated isoprene-styrene / methyl methacrylate ternary block copolymer was obtained. The refractive index (Nd) of the resin (A-3) at 20 ° C. was 1.487, and the temperature dependence coefficient (ΔNd) of the refractive index was −2.60 × 10 ⁻⁴ / ° C.

Production of Resin (A-4) A reaction vessel equipped with a reflux condenser was charged with 100 parts of ion-exchanged water containing a suspending / dispersing agent, and then 85 parts of methyl methacrylate, 15 parts of methyl acrylate, and lauroyl peroxide 0. A mixed solution of 0.5 parts of n-octyl mercaptan and 0.7 part of n-octyl mercaptan was charged and polymerized under stirring in a nitrogen atmosphere at 80 ° C. for 2 hours and then at 95 ° C. for 1 hour to give an intrinsic viscosity of 0.
31 dl / g resin beads were obtained. 30 parts of the obtained resin beads and 70 parts of the resin (A-1) were uniformly melt mixed to obtain a resin (A-4). The refractive index (Nd) of the resin (A-4) at 20 ° C. was 1.496, and the temperature dependence coefficient (ΔNd) of the refractive index was −2.28 × 10 ⁻⁴ / ° C.

Production of Resin (A-5) A reaction vessel equipped with a reflux condenser was charged with 100 parts of ion-exchanged water containing a suspending / dispersing agent, and then 95 parts of methyl methacrylate, 5 parts of methyl acrylate and lauroyl peroxide. A mixed solution of 4 parts and 0.2 part of n-octyl mercaptan was charged, and the mixture was stirred at 80 ° C. under a nitrogen atmosphere for 2 hours.
Polymerization for 1 hour at 95 ° C for 1 hour
4 dl / g resin (A-5) beads were obtained. Resin (A-
The refractive index (Nd) of 5) at 20 ° C. is 1.490,
The temperature dependence coefficient (ΔNd) of the refractive index is −0.79 × 10 ⁻⁴
/ ° C.

Production of crosslinked resin (B-1) Ion-exchanged water 200 in a reaction vessel equipped with a reflux condenser.
Part, 1 part of sodium dioctylsulfosuccinate were charged and heated to 70 ° C. under stirring under a nitrogen atmosphere, then 60 parts of methyl methacrylate, 10 parts of styrene, 1 part of allyl methacrylate and 1 part of 1% potassium persulfate aqueous solution. The mixture was charged and reacted for 60 minutes to complete the polymerization to form an inner layer. Next, after charging 0.5 part of a 1% potassium persulfate aqueous solution, 25 parts of methyl methacrylate, 5 parts of methyl acrylate and n-
The total amount of the monomer mixture consisting of 0.24 parts of octyl mercaptan was continuously added dropwise over 30 minutes, and then maintained for 60 minutes to complete the polymerization to form an outer layer.
A resin latex having a two-layer structure of μm was obtained. The intrinsic viscosity of the resin obtained by polymerizing only the outer layer under the same conditions is 0.28 dl.
/ G. The refractive index (Nd) of the inner layer at 20 ° C
Is 1.500, and the temperature dependence coefficient of refractive index (ΔNd)
Was -0.81 x 10 ^-4 / ° C. The obtained latex was added to a 3% aqueous magnesium sulfate solution, coagulated by salting out, washed with water and dried to obtain a crosslinked structure resin (B-1).

Production of crosslinked structure resin (B-2) Ion-exchanged water 200 in a reaction vessel equipped with a reflux condenser.
Part, 1 part of sodium dioctylsulfosuccinate were charged and heated to 70 ° C. under stirring in a nitrogen atmosphere, then 60 parts of methyl methacrylate, 10 parts of styrene, 1 part of diethylene glycol dimethacrylate, 1 part of 1% potassium persulfate aqueous solution. The mixture was charged, reacted for 60 minutes and polymerized to obtain a crosslinked resin latex having a particle diameter of 0.16 μm. The refractive index (Nd) of the crosslinked resin layer at 20 ° C. is 1.500, and the temperature dependence coefficient (ΔNd) of the refractive index is −0.81 × 10 ⁻⁴ / ° C.
Met.

The obtained latex was added to a 3% aqueous magnesium sulfate solution, coagulated by salting out, washed with water and dried to obtain a crosslinked resin (B-2).

Production of crosslinked structure resin (B-3) In the same manner as in the crosslinked structure resin (B-1), 30 parts of methyl methacrylate, 20 parts of styrene and 1.0 part of 1,3-butylene glycol dimethacrylate were prepared. Inner layer formed by polymerization, methyl methacrylate 45 parts, ethyl acrylate 5
Part, and an outer layer formed by polymerizing 0.3 part of n-octyl mercaptan, to obtain a two-layer structure resin latex having a particle diameter of 0.12 μm. The intrinsic viscosity of the resin obtained by polymerizing only the outer layer under the same conditions was 0.34 dl / g. The refractive index (Nd) of the inner layer at 20 ° C. is 1.530, and the temperature dependence coefficient (ΔNd) of the refractive index is −0.95 × 10 ⁻⁴ /
° C.

The obtained latex was added to a 3% aqueous magnesium sulfate solution, salted out and coagulated, washed with water and dried to obtain a crosslinked resin (B-3).

Production of crosslinked structure resin (B-4) By the same method as in the crosslinked structure resin (B-1), 58 parts of methyl methacrylate, 2 parts of methyl acrylate and 0.5 part of allyl methacrylate are polymerized. Thus, a two-layer resin latex having a particle diameter of 0.23 μm was obtained, which was composed of an inner layer formed by polymerization and an outer layer formed by polymerizing 39 parts of methyl methacrylate, 1 part of methyl acrylate and 0.3 part of n-octyl mercaptan. The intrinsic viscosity of the resin obtained by polymerizing only the outer layer under the same conditions was 0.29 dl / g. The refractive index (Nd) of the inner layer at 20 ° C. was 1.489, and the temperature dependence coefficient (ΔNd) of the refractive index was −0.76 × 10 ⁻⁴ / ° C.

The obtained latex was freeze-coagulated at -20 ° C., then thawed in warm water at 80 ° C., washed with water and dried to obtain a crosslinked resin (B-4).

Production of crosslinked structure resin (B-5) An inner layer formed by polymerizing 50 parts of butyl acrylate, 10 parts of styrene and 1 part of allyl methacrylate by a method similar to that of the resin having crosslinked structure (B-1), Methyl methacrylate 39
Part, methyl acrylate 1 part, n-octyl mercaptan 0.3 part polymerized as an outer layer, particle diameter 0.08
A resin latex having a two-layer structure of μm was obtained. The resin obtained by polymerizing only the outer layer under the same conditions has an intrinsic viscosity of 0.48 dl
/ G. The refractive index (Nd) of the inner layer at 20 ° C
Is 1.487, and the temperature dependence coefficient of refractive index (ΔNd)
Was -1.42 x 10 ^-4 / ° C.

The obtained latex was freeze-coagulated at -20 ° C, then thawed in warm water at 80 ° C, washed with water and dried to obtain a crosslinked resin (B-5).

Examples 1 to 7 and Comparative Examples 1 to 2 Resin A and resin B having a crosslinked structure were mixed in a mixer with the composition shown in Table 1 and fed into a closed kneader under a nitrogen atmosphere,
Melt mixing was performed under the conditions of 230 ° C. and 100 rpm for 5 minutes.
A 2 mm flat plate was molded from the obtained mixture by hot press molding, and its optical properties were measured. The results are shown in Table 1.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION The resin composition having a whitening property according to the temperature of the present invention has a very remarkable change in transparency due to a temperature difference of 20 to 30 ° C., and by making use of this effect, it can be used as an injection molded article, a sheet and a film. It can be applied to carports, shopping arcades and eaves, exteriors, greenhouses, car sun visors, and other applications for dimming purposes.

Claims (2)

[Claims] 1. A thermoplastic resin A composed of 10 to 90 parts by weight and a crosslinked structure resin B of 90 to 10 parts by weight. The gradient of the refractive index of the thermoplastic resin A due to temperature and the crosslinked structure resin B in at least one inner layer. A resin composition characterized in that the difference (ΔN) between the refractive index and the temperature-dependent inclination satisfies the formula (1). [Equation 1] (However, NdA ^q and NdA ^p are the refractive indexes of the thermoplastic resin A at q ° C. and p ° C., respectively, and
dX ^q and NdX ^p represent the refractive index of the inner layer X of the crosslinked resin B at q ° C. and p ° C., respectively. ) 2. The crosslinked resin B comprises a multilayer structure,
Each inner layer is substantially crosslinked, the sum of the weight of each inner layer is 30% by weight or more of the crosslinked resin B, and the outermost layer thereof has fluidity, and in the blend with the thermoplastic resin A. It has good compatibility and transparency.
The resin composition according to.