JP2002293838A - Flexible acrylic copolymer, its producing method and flexible resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel flexible acrylic copolymer replaced with a flexible vinyl chloride resin which does not contain a halogen atom, a production method thereof and a flexible resin composition containing the copolymer. SOLUTION: The flexible acrylic copolymer comprises a copolymer of a methyl methacrylate of 40-70 wt.% and a n-butyl acrylate of 60-30 wt.% and it has the reduced viscosity of 0.9-3.0 dl/g, a glass transition point of 90 deg.C or less and tanδ at 20 deg.C of 0.07 or more. The copolymer is produced by suspension polymerization or the like. The flexible resin composition is obtained by adding a plasticizer to the copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a flexible soft acrylic copolymer, a method for producing the same, and a flexible resin composition.

[Prior art]

In general, as a soft resin, a soft vinyl chloride resin is well known, and is widely used from various films to applications such as tents for simple warehouses, hoods for trucks, flexible containers, tents for open storage, and the like. However, recently, from the viewpoint of environmental protection, a soft resin containing no halogen atom has been demanded.

[0003]

SUMMARY OF THE INVENTION The present invention provides a novel soft acrylic copolymer containing no halogen atom, which replaces the soft vinyl chloride resin, a method for producing the same, and a soft resin composition containing the copolymer. It is to be.

[0004]

The soft acrylic copolymer according to the present invention for solving the above-mentioned problems comprises 40 to 70% by weight of methyl methacrylate and n-butyl acrylate.
And a reduced viscosity of 0.9 to 30% by weight.
~ 3.0 dl / g, glass transition point is 90 ° C or less, 20 ° C
Is characterized by having a tan δ of 0.07 or more. Preferably, the soft acrylic copolymer of the present invention,
It is preferable that the molecule contains 15% by weight or more of oxygen atoms.

[0005] The method for producing a soft acrylic copolymer according to the present invention is characterized in that methyl methacrylate is 40 to 70% by weight.
And 60 to 30% by weight of n-butyl acrylate for suspension polymerization.

[0006] The soft resin composition of the present invention is characterized in that a plasticizer is added to the soft acrylic copolymer.
The amount of the plasticizer to be added is suitably 100 parts by weight or less (however, it must not be 0 parts by weight) based on 100 parts by weight of the soft acrylic copolymer.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The soft acrylic copolymer of the present invention is obtained by polymerizing a monomer mixture of 40 to 70% by weight of methyl methacrylate and 60 to 30% by weight of n-butyl acrylate. Consists of a polymer. When the methyl methacrylate exceeds the above range or the n-butyl acrylate falls below the above range, the glass transition point becomes high and the softness becomes poor. On the other hand, if methyl methacrylate is below the above range or if n-butyl acrylate exceeds the above range, the glass transition point becomes too low, making it difficult to dry the product, resulting in extremely poor handling. Not preferred.

The copolymer of the present invention has a glass transition point of 90.
° C or less, preferably 0 to 90 ° C, more preferably 30 to 90 ° C.
70 ° C., and tan δ at 20 ° C. is 0.07 or more, preferably 0.07-1, more preferably 0.08.
０．５0.5 is required. Glass transition point is 90
If the temperature exceeds ℃, the flexibility becomes poor, which is not preferable. In order to make the glass transition point 90 ° C. or lower, the composition ratio of the monomer may be appropriately selected. As the ratio of n-butyl acrylate increases, the glass transition point tends to decrease. The glass transition point is preferably 0 ° C. or higher for imparting heat resistance to the obtained copolymer. On the other hand, if tan δ is less than 0.07, the flexibility becomes poor, which is not preferable.

The copolymer of the present invention contains at least 15% by weight of oxygen atoms in the molecule, preferably 15 to 50% by weight.
More preferably, the content is 20 to 40% by weight. If the number of oxygen atoms in the molecule is less than 15% by weight, the scratch resistance may be reduced.

Further, the copolymer of the present invention preferably has a particle shape, and has an average particle diameter of 100 μm or more.
Further, the thickness is preferably 200 μm or more, 800 μm or less, and more preferably 500 μm or less.

In order to produce the copolymer of the present invention, the above-mentioned monomer mixture, radical polymerization initiator, water and dispersant are placed in a reactor, and the mixture is heated with stirring to carry out suspension polymerization. Examples of the radical polymerization initiator include lauroyl peroxide, benzoyl peroxide, di-t-butyl peroxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, and t-butylperoxyisobutyrate.
Peroxide initiators such as -butylperoxypivalate, t-butylperoxybenzoate, t-butylperoxyacetate, diisopropylperoxycarbonate and di-s-butylperoxycarbonate;
An azo initiator such as 2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile) is exemplified.

As the suspension stabilizer used in the suspension polymerization of the present invention, well-known suspension stabilizers may be used, for example, alkali salts of polymethacrylic acid (such as sodium salt and potassium salt) and sodium dodecylbenzenesulfonate. , Sodium lauryl sulfate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, boric acid, sodium carbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium sulfate and the like. In order to adjust the molecular weight of the polymer, a known chain transfer agent may be used. Examples of the chain transfer agent include alkyl mercaptan, alkyl sulfide, alkyl disulfide, thioglycolic acid ester, and α-methylstyrene dimer.

The polymerization is preferably carried out at a relatively low temperature so that no monomer remains.
After heating at 30 ° C for about 30 minutes to 3 hours, raise the temperature to 80-1
The polymerization reaction is completed by heating at 30 ° C. for about 10 minutes to 2 hours. Thus the average particle size is 100-800μ
About m copolymer particles are obtained.

Although this copolymer is basically a random copolymer, it is obtained by using a dye (such as ruthenium tetroxide) suitable for selectively dyeing n-butyl acrylate. When the polymer particles were dyed, and then the cut surface of the particles was observed with a microscope, it was found that a large number of n-butyl acrylate polymers were dispersed in the polymer of methyl methacrylate in the form of fine particles in the form of dots. It forms an island structure. Since the polymer of methyl methacrylate is relatively hard and the polymer of n-butyl acrylate is relatively soft,
It is presumed that the above sea-island structure influences the development of softness. Note that similar copolymer particles can be obtained by employing emulsion polymerization instead of suspension polymerization.

The obtained copolymer resin according to the present invention comprises:
Although it has high flexibility by itself, a plasticizer may be added as necessary. Examples of the plasticizer include a citrate-based plasticizer such as acetyl tributyl citrate (ATBC), a phthalate-based plasticizer such as dioctyl phthalate (DOP), and a trimellitic acid such as 2-ethylhexyl ester of trimellitic acid. Ester plasticizers, aliphatic dibasic acid esters such as dioctyl adipate, long-chain fatty acid ester plasticizers such as butyl oleate, epoxy plasticizers having an epoxy group in the molecule, phosphate esters such as tricresyl phosphate And polyester plasticizers obtained by polyesterification of dibasic acids such as adipic acid, sebacic acid and phthalic acid with 1,2-propylene glycol and the like. Among them, ATBC is preferred because it can be used for food packaging and the like. The amount of the plasticizer is 0 to 100 parts by weight, preferably 0 to 30 parts by weight, based on 100 parts by weight of the copolymer resin.

When a plasticizer is added to the copolymer resin according to the present invention, it is uniformly mixed using, for example, a ribbon blender or a Henschel mixer to obtain a resin composition. In the present invention, in addition to the plasticizer, other known additives depending on the use, such as antioxidants (hindered phenols, phosphoric acids, sulfures, etc.), ultraviolet absorbers, weathering agents (hindered amine-based stabilizers) Agents), release agents, flame retardants, dyes, pigments,
It is also possible to mix an inorganic filler or the like with the copolymer resin.

The copolymer resin according to the present invention, into which additives such as a plasticizer are mixed as required, can be formed into a flexible sheet or film having a predetermined thickness by extrusion molding or the like. The resulting sheet or film can be used for various applications as it is, and can also be used by applying an adhesive to one or both surfaces of the fiber base material, or by applying a thermal bond without using an adhesive. it can. Further, the copolymer resin according to the present invention can be used by being mixed with other resins by utilizing its softness.

[0018]

EXAMPLES The copolymer of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. The measurement and evaluation methods performed in the examples are as follows.

(1) Reduced Viscosity The resin was dissolved in chloroform at a concentration of 1%, and the viscosity of the solution was measured at 25 ° C. using an Ubbelohde viscometer. (2) The tan δ sample was pressed to prepare a measurement sheet having a width of 3 mm and a thickness of 0.3 mm, and a viscoelasticity measurement device “DMS200” manufactured by Seiko Electronics Industry Co., Ltd. was used.
The measurement was performed at 0 mm, at a heating rate of 5 ° C./min, and at a frequency of 5 Hz. (3) Glass transition point (Tg) The measurement was performed according to JIS K7121 using “DSC RDC220” manufactured by Seiko Electronics Industries, Ltd.
The maximum value of the derivative of the C curve was defined as the glass transition point. (4) Low resilience As shown in FIG. 1, the sample 1 is cut into a size of 3 cm × 15 cm, wound around a cylinder 2 having a diameter of 3.5 cm at a temperature of 23 ° C., and released to its original shape when released Was measured in seconds. (5) Heat resistance (oven hanging) A sample piece cut into 2 cm x 15 cm is hung in an oven set at 40 ° C, and 500 mm is placed on the lower end of the sample piece.
g was suspended and the elongation after applying a load for 10 minutes was measured.

Example 1 (Production of a methyl methacrylate-butyl acrylate copolymer) In a 200 L SUS autoclave, 50 parts by weight of methyl methacrylate, 50 parts by weight of butyl acrylate, 0.45 parts by weight of lauroyl peroxide, 0.1 parts by weight of dodecyl mercaptan, 120 parts by weight of ion-exchanged water,
3% by weight of a 1.2% sodium polymethacrylate aqueous solution,
0.25 parts by weight of disodium hydrogen phosphate heptahydrate and 0.29 parts by weight of monosodium hydrogen phosphate were added and mixed, and heated to raise the temperature to start polymerization at 75 ° C.
Polymerization was performed at 00 ° C. for 20 minutes. After polymerization, washing, dehydration and drying were performed to obtain a granular polymer. This polymer had a butyl acrylate content of 50% by weight, an intramolecular oxygen atom content of 29% by weight, a reduced viscosity of 1.5 dl / g, a Tg of 35.4 ° C., and a ta
n δ 0.142, average particle diameter 500 μm. In addition,
Butyl acrylate (BA) in the polymer was measured by the following method. That is, the sample was put into a furnace heated to 540 ° C. and pyrolyzed, the decomposed gas was measured by gas chromatography, and the peak intensity of BA was quantified by comparing with the BA amount of the standard sample. Further, the polymer obtained above was processed into a 150 μm thick press sheet, and the low resilience and heat resistance of a sample obtained by heat-bonding the press sheet to both sides of the fiber base fabric at 150 ° C. were measured. did. As a result, the low resilience was 30 seconds, and the heat resistance (elongation) was 0.3 mm.
Met. From this, the polymer has flexibility,
It turns out that it is also excellent in heat resistance.

Example 2 The same press sheet as in Example 1 was examined for low resilience in the same manner as in Example 1 without sandwiching the fiber base fabric. The low resilience was 20 seconds, which was sufficiently high. It had flexibility.

Example 3 Example 1 was repeated except that the amount of methyl methacrylate was changed to 70 parts by weight, the amount of butyl acrylate was changed to 30 parts by weight, and the amount of dodecyl mercaptan was changed to 0.11 part by weight. By operating in the same manner as in Example 1, a granular polymer was obtained. This polymer had a butyl acrylate content of 30% by weight, an intramolecular oxygen atom content of 30% by weight, a reduced viscosity of 1.6 dl / g, and a Tg of 6
8.0 ° C., tan δ 0.22, average particle size 500 μm. When 100 parts by weight of the obtained granular polymer was mixed with 6 parts by weight of tributyl acetylcitrate (ATBC), and the mixture was processed, a press sheet having a thickness of 300 μm was examined for low resilience. The property was 13 seconds and had sufficiently high flexibility.

[0023]

According to the present invention, there can be provided a soft acrylic copolymer containing no halogen atom and a soft resin composition containing this copolymer, which can replace the soft vinyl chloride resin.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an outline of a low resilience test.

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Claims (8)

[Claims] 1. A copolymer of 40 to 70% by weight of methyl methacrylate and 60 to 30% by weight of n-butyl acrylate, having a reduced viscosity of 0.9 to 3.0 dl / g and a glass transition point of 90 ° C. Hereinafter, a soft acrylic copolymer having a tan δ at 20 ° C of 0.07 or more. 2. The soft acrylic copolymer according to claim 1, which contains at least 15% by weight of oxygen atoms in the molecule. 3. The soft acrylic copolymer according to claim 1, wherein the glass transition point is 0 to 90 ° C. and the tan δ at 20 ° C. is 0.07 to 1. 4. A particle having a shape having an average particle size of 100
The soft acrylic copolymer according to any one of claims 1 to 3, which has a thickness of from 800 to 800 µm. 5. The method according to claim 1, wherein 40 to 70% by weight of methyl methacrylate and 60 to 30% by weight of n-butyl acrylate are mixed and subjected to suspension polymerization. A method for producing a soft acrylic copolymer. 6. The soft acrylic copolymer according to claim 5, wherein the polymerization is carried out by heating at 60 to 80 ° C. for 30 minutes to 3 hours, then increasing the temperature and heating at 80 to 130 ° C. for 10 minutes to 2 hours. A method for producing a polymer. 7. A soft resin composition, wherein a plasticizer is added to the soft acrylic copolymer according to any one of claims 1 to 4. 8. The amount of the plasticizer to be added is 100 parts by weight or less based on 100 parts by weight of the soft acrylic copolymer (however,
It must not be 0 parts by weight. The soft resin composition according to claim 6, wherein