JP2809943B2 - Composition for molding sheet material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for molding a sheet having excellent transparency.

[0002]

2. Description of the Related Art Various films or sheets are used for packaging, protection, decoration and the like. Among materials used for films and sheets, polyolefins such as polyethylene and polypropylene have insufficient transparency and flexibility.

Further, the strength of a film of an ethylene-vinyl acetate copolymer is insufficient, and the moisture absorption of a PVA film may become a problem.

A material satisfying both transparency and flexibility is a soft vinyl chloride film. Soft vinyl chloride contains a low-molecular-weight plasticizer such as DOP, which causes bleeding and contaminates materials in contact. In addition, there is also a problem that toxic gas is generated when soft vinyl chloride is burned. For this reason, there has recently been a tendency to replace soft vinyl chloride with other materials.

[0005]

[0008] The present invention, Ri Do from a mixture of hydrogenated isoprene block copolymer and polypropylene having a specific structure is excellent in transparency,
It is an object of the present invention to provide a material that is flexible, has no bleed, and does not generate toxic or harmful gas when burned, and has excellent safety.

[0006]

According to the present invention, the above problems are caused by the following problems: (a) a block (A) comprising at least one vinyl aromatic monomer and having a number average molecular weight of 2,500 to 40,000; Abbreviated as aromatic block (A)
Referred to as it is], isoprene or isoprene - consists butadiene mixture, 3,4 bond and 1,2
90 to 10 parts by weight of a hydrogenated product of a block copolymer having a number average molecular weight of 30,000 to 300,000 and comprising a block (B) having a bond content of 25% or more, and (b)
The problem is solved by a sheet composition comprising 10 to 90 parts by weight of polypropylene.

Hereinafter, the present invention will be described in more detail.

The vinyl aromatic block (A) of the block copolymer, which is the component (a) used in the present invention, comprises
The component to be formed is an aromatic vinyl monomer, and specific examples thereof include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-methylstyrene, 4-propylstyrene,
4-cyclohexylstyrene, 4-dodecylstyrene,
Examples thereof include 2-ethyl-4-benzylstyrene and 4- (phenylbutyl) styrene, with styrene being most preferred.

The number average molecular weight of the vinyl aromatic block (A) is in the range of 2,500 to 40,000. Vinyl aromatic
When the number average molecular weight of the block (A) is less than 2500, the performance as a composition is deteriorated, and when it exceeds 40000, the melt viscosity becomes too high, and the mixing with other components of the present invention does not work well, which is not preferable. .

The ratio of the vinyl aromatic block (A) in the block copolymer is in the range of 5 to 50% by weight.
It is preferred that

The component constituting the block (B) of the block copolymer used in the present invention is isoprene or an isoprene-butadiene mixture ,
Preferably it is isoprene. Isoprene-butadiene
When a mixture is used, any of random, block, and tapered may be used. In this case, the ratio of butadiene is 40% or less. If the proportion of butadiene exceeds 40%, the transparency is undesirably reduced.

In the block copolymer (B) of the present invention, the content of 3,4 bonds and 1,2 bonds (hereinafter sometimes collectively referred to as "vinyl bond content") of the block (B) is at least 25% (100%). % May be used). When the vinyl bond content is less than 25% , a sheet-like molded product having sufficient transparency cannot be obtained, which is not preferable.

The block (B) of the block copolymer
Number average molecular weight depends on the elastic properties of the block copolymer.
From the viewpoints of fluidity and fluidity, it is desirable that it is in the range of 10,000 to 200,000.

The number average molecular weight of the block copolymer used as the component ( a ) in the present invention is from 30,000 to 3,000.
It must be in the range of 00. Molecular weight 3000
If it is smaller than 0, the mechanical properties of the block copolymer itself decrease, and when it is made into a composition, its strength is undesirably reduced. On the other hand, if it exceeds 300,000, the workability deteriorates, which is not preferable.

The block copolymer is A (BA)
A block form represented by n, (AB) n is preferably used. Here, A represents a block composed of an aromatic vinyl monomer, B represents a block composed of isoprene or isoprene-butadiene, and n is an integer of 1 or more. Of these, those in the form of ABA are most preferably used.

In the present invention, the hydrogenated block copolymer is obtained by the following various methods.

First, the production of the block copolymer is as follows:
The vinyl aromatic monomer an alkyl lithium compound as an initiator, followed by isoprene comma others isoprene - method of successive polymerization of butadiene mixtures, isoprene or isoprene subsequently (ii) a vinyl aromatic monomer - polymerizing butadiene mixture, which By a coupling agent , or (c) a method of sequentially polymerizing isoprene or an isoprene-butadiene mixture using a dilithium compound as an initiator, followed by a vinyl aromatic monomer.

Examples of the alkyl lithium compound include an alkyl compound having an alkyl residue having 1 to 10 carbon atoms, and particularly preferred are methyl lithium, ethyl lithium, pentyl lithium and butyl lithium. As the coupling agent, dichloromethane, dibromomethane, dichloroethane, dibromoethane, dibromobenzene and the like are used. Examples of the dilithium compound include naphthalenedilithium, dithiohexylbenzene, and the like. The amount used is of a nature determined by the required molecular weight,
Relative to 100 parts by weight of all the monomers used in the polymerization, generally initiator 0.01 to 0.2 parts by weight, when using a coupling agent, about 0.04 to 0.8 parts by weight of the coupling agent Use within the range .

The isoprene or isoprene - butadiene part, to the vinyl bond content to have 25% or more microstructures, isoprene or isoprene - Lewis base is used as a cocatalyst in the polymerization of butadiene mixture . Examples of Lewis bases include dimethyl ether, diethyl ether, ethers such as tetrahydrofuran, ethylene glycol dimethyl ether,
Glycol ethers such as diethylene glycol dimethyl ether, triethylamine, N, N, N ', N'-
Examples include amine compounds such as tetramethylethylenediamine (TMEDA) and N-methylmorpholine. These Lewis bases are used in an amount of about 0.1 to 1000 times the mole number of lithium of the polymerization initiator.

In the polymerization, it is preferable to use a solvent in order to facilitate the control. As the solvent, an organic solvent inert to the polymerization initiator is used. Particularly, the carbon number is 6-1.
2, aliphatic, alicyclic and aromatic hydrocarbons are preferably used. Examples include hexane, heptane, cyclohexane, methylcyclohexane, benzene and the like.

The polymerization is carried out by any of the polymerization methods from 0 to 0.
The reaction is performed at a temperature of 80 ° C. for a period of 0.5 to 50 hours.

The block copolymer is hydrogenated by a known method. For the hydrogenation reaction, a method in which hydrogen in a molecular state is reacted with a known hydrogenation catalyst in a state of being dissolved in a hydrogenation catalyst and a solvent inert to the reaction is preferably used. The catalyst used is Raney nickel or Pt, Pd, R
Heterogeneous catalysts such as those in which a metal such as u, Rh, and Ni are supported on a carrier such as carbon, alumina, and diatomaceous earth, or a Ziegler-based catalyst composed of a combination of a transition metal and an alkyl aluminum compound, an alkyl lithium compound, or the like. Used. The reaction is carried out at a hydrogen pressure from normal pressure to 200 kg / cm.
^{2. The} reaction temperature is from room temperature to 250 ° C, the reaction time is 0.1
It is carried out in the range of 100 hours. The block copolymer after the reaction is obtained by coagulating the reaction solution with methanol or the like and then heating or drying under reduced pressure, or by pouring the reaction solution into boiling water and removing the solvent by azeotropic distillation, and then heating or drying under reduced pressure. can get.

The hydrogenation rate of the hydrogenated block copolymer should be 50% or more, preferably 70% or more. If it is lower than 50%, sufficient transparency cannot be obtained, which is not preferable.

As the polypropylene of the component (b) used in the present invention, homo, random and block polymers are used.

The polypropylene has an MFR of 0.1 to 800.
And more preferably in the range of 2 to 200.

In the present invention, the polypropylene is not limited to one type, and two or more types may be mixed and used.

The composition of the present invention comprises a hydrogenated component (a).
90 to 10 parts by weight of the block copolymer and 10 to 90 parts by weight of the polypropylene as the component (b) are mixed.
You. (B) If the ratio of the polypropylene as the component is less <br/> than this, mechanical strength of the composition becomes insufficient.
Also, if the ratio of polypropylene is larger than this,
The transparency of the resulting sheet-like molded product is reduced .

Various additives are used in the composition of the present invention to such an extent that its properties are not impaired. Examples thereof include 0.01 to 5 parts by weight of an antioxidant, an ultraviolet absorber, a coloring agent, a crystal nucleating agent and the like based on 100 parts by weight of the composition.

The composition of the present invention can be used by blending with another polymer as long as the purpose of the present invention is not impaired. Examples thereof include hydrogenated polyisoprene, hydrogenated polybutadiene, hydrogenated styrene-butadiene copolymer, hydrogenated styrene-isoprene copolymer, hydrogenated styrene-butadiene block copolymer, and hydrogenated styrene-isoprene block copolymer. Coalesce, butyl rubber, polyisobutylene, polybutene, ethylene-propylene rubber,
Examples thereof include polyethylene and atactic polypropylene, and are not limited to one type, and two or more types may be used in combination. The blend amount of these polymers is about 50 parts by weight based on 100 parts by weight of the hydrogenated block copolymer of the component (a).
Not more than parts by weight.

The composition of the present invention may optionally contain
It is also possible to use a peroxide by crosslinking with a usual crosslinking method using a peroxide.

The composition of the present invention is kneaded by a kneader, an extruder, and a roll, and is molded and used by a calender roll, an extruder, an injection molding machine, and inflation.

[0032]

The present invention will be described more specifically with reference to the following examples.

Each measured value in the examples was obtained by the following method.

The molecular weight was determined by GPC.

The microstructure was measured by NMR spectrum,
The content of 3,4 bonds and 1,2 bonds was calculated from the ratio of the peaks of 3.4 bonds, 1,2 bonds at 4.8 ppm and 5.8 ppm.

The hydrogenation rate was calculated from the ratio of the iodine values of the block copolymer before and after the hydrogenation reaction.

For the transparency, a light transmittance of 400 to 800 nm was measured.

The flexibility was measured by an ASTM D hardness tester. Reference Example 1 (Preparation of hydrogenated block copolymer of component (a) in the present invention) In a pressure-resistant reactor replaced with dry nitrogen, cyclohexane as a solvent, n-butyllithium as a polymerization catalyst,
Using TMEDA as a vinylating agent, a styrene monomer, an isoprene monomer, and a styrene monomer were added in this order, followed by polymerization to obtain ABA block copolymers (I) and (II). The obtained block copolymers (I) and (II) were subjected to a hydrogenation reaction in cyclohexane using Pd—C as a hydrogenation catalyst at a hydrogen pressure of 20 kg / cm ² to obtain a hydrogenated block copolymer (I). ) And (II).

Table 1 shows these molecular characteristics. Reference Example 2 (Preparation of hydrogenated styrene-isoprene block copolymer) A hydrogenated styrene-isoprene block copolymer was obtained in the same manner as in Reference Example 1 except that no vinylating agent was used. The resulting hydrogenated styrene - isoprene block copolymer has a number average molecular weight = 120000, a number average molecular weight of the styrene block = 8000, Sutaira isoprene block
Equivalent molecular weight = 100000, vinyl bond content = 7.6
%, Hydrogenation rate = 95.4%. Examples 1 to 4 The hydrogenated block copolymers (I) and (I) obtained in Reference Example 1
I) was compounded with a kneader according to the formulation shown in Table 2 by 210.
The mixture was kneaded at ℃ to obtain a composition.

The obtained composition was press-molded at 210 ° C. into a sheet having a thickness of 1 mm, and the light transmittance and the hardness were measured. Comparative Examples 1 to 4 The block copolymers (I) and (I) obtained in Reference Examples 1 and 2
I), a hydrogenated styrene-isoprene copolymer and a hydrogenated styrene-butadiene block copolymer (TAFTEC H1052 manufactured by Asahi Kasei) were kneaded and sheet-formed in the same manner as in the examples according to the composition shown in Table 2, and the light transmittance was measured. And hardness were measured.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

By combining a hydrogenated block copolymer having a specific structure with polypropylene, a composition for molding a sheet having excellent flexibility and transparency is provided.

Claims (1)

(57) [Claims] (1) A block (A) comprising at least one vinyl aromatic monomer and having a number average molecular weight of 2,500 to 40,000, and isoprene or an isoprene-butadiene mixture, having 3,4 bonds and 1,2 bonds It contains 90 to 10 parts by weight of a hydrogenated product of a block copolymer having a number average molecular weight of 30,000 to 300,000 composed of blocks (B) having a content of 25% or more, and (b) 10 to 90 parts by weight of polypropylene. A composition for molding a sheet material, comprising: