JPH05117492A - Styrene-butadiene block copolymer composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which has excellent antistatic and non-fogging effects without detriment to surface properties, transparency and impact resistance. CONSTITUTION:A styrene-butadiene block copolymer is blended with a mixture of a fatty acid ester of glycerin, a fatty acid ester of sorbitan and/or an alkylene oxide adduct thereof to obtain the title composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a styrene-butadiene (hereinafter sometimes referred to as SB) block copolymer composition, and more specifically to an SB block copolymer composition having excellent antistatic properties and antifogging properties. ..

[0002]

Since the SB copolymer resin exhibits excellent performances in impact resistance and transparency, it has been widely used in packaging materials such as blister packs, trays and various containers. However, since the surface is hydrophobic, it is easily charged by static electricity, dust is likely to adhere, and electric shock is likely to occur. In addition, when packaging foods and the like, water drops are attached to cause fogging, which significantly reduces the value as a packaging material.

Therefore, in order to impart antistatic property and antifogging property to such SB copolymer resin, conventionally, an antistatic agent composed of various kinds of surfactants is applied to the surface of the molded product, or at the time of molding process. A method of kneading various antistatic agents into the SB copolymer resin is adopted.

However, although the SB copolymer resin obtained by the former method is excellent in immediate effect, the surfactant on the surface of the molded product is removed by rubbing, washing, etc.,
It is difficult to maintain the antistatic effect and antifogging property for a long period of time. In the latter method, when an anionic surfactant commonly used in styrene resins is added, the transparency characteristic of the SB copolymer is hindered, and when a nonionic surfactant is added, Due to the rubbery properties of the polybutadiene portion, there are problems that the amount of bleeding is too large, the surface quality of the molded product is deteriorated, and the sustainability of the effect cannot be obtained.

[0005]

In view of such circumstances, the present inventors have obtained an SB block copolymer composition having an excellent antistatic effect and antifogging effect, which is excellent in durability without deteriorating the surface properties. As a result of intensive studies, fatty acid ester of glycerin and fatty acid ester of sorbitan and /
Further, they have found that the composition for the above purpose can be obtained by blending the alkylene oxide adduct with the alkylene oxide adduct into the SB block copolymer composition, and completed the present invention.

That is, the present invention is characterized in that the styrene-butadiene block copolymer is blended with a mixture of a fatty acid ester of glycerin and a fatty acid ester of sorbitan and / or an alkylene oxide adduct thereof. A butadiene block copolymer composition is provided.

The SB block copolymer used in the present invention is produced, for example, by polymerizing 80 to 40 parts by weight of a styrene monomer and 20 to 60 parts by weight of a butadiene monomer using an organolithium-based polymerization initiator. To be done. They have the following structural formulas (1) to (5)

[0008]

[Chemical 1]

(In the formula, S represents a styrene block, and B represents
Represents a butadiene block, C represents a coupling agent, and n represents a number of 1 to 5), and is a linear block copolymer or a branched block copolymer. this house,
The butadiene rubber component represented by B is preferably 7% by weight or more of the whole.

The SB block copolymer includes polystyrene, styrene-acrylonitrile copolymer, styrene-
A styrene-based polymer such as a methyl methacrylate copolymer may be blended, and the proportion of the styrene-based polymer that can be blended is 90% by weight or less based on the total amount of the SB block copolymer. Also in this case, the content of the butadiene rubber component in the entire resin blend is preferably 7% by weight or more. If it is less than this, the excellent impact resistance, which is a characteristic of the SB block copolymer, cannot be exhibited.

The fatty acid ester of glycerin used in the present invention is an ester of fatty acid having 8 to 22 carbon atoms and glycerin, and examples of the above fatty acid include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid. , Oleic acid, linoleic acid, behenic acid and mixed acids thereof. Any fatty acid can be used, but stearic acid is particularly preferable. Generally, in the esterification reaction of a fatty acid and glycerin, a mixture of a diester, a triester and the like can be obtained in addition to the monoester. In the present invention, the monoester content is preferably as high as possible. Therefore, high-purity glycerin monostearate is particularly preferable.

The fatty acid ester of sorbitan used in the present invention is obtained by a cyclization / esterification reaction of sorbitol and a fatty acid having 8 to 22 carbon atoms. Preferred examples of fatty acid include capric acid and laurin. Acids, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, behenic acid and mixed acids thereof. Of these, palmitic acid is particularly preferable. Examples of the alkylene oxide adduct of sorbitan fatty acid ester include those obtained by adding ethylene oxide or propylene oxide to the sorbitan fatty acid ester obtained by the above reaction. The fatty acid ester of sorbitan is also obtained as a mixture of monoester, diester, triester and the like like the fatty acid ester of glycerin, but sorbitan monofatty acid ester having a high monoester content is preferable. The number of moles of alkylene oxide added is preferably 40 mol or less, and more preferably 5 to 25 mol, per 1 mol of ester.

Even when only fatty acid ester of glycerin is added to the SB block copolymer, a certain antistatic effect can be obtained, but when used alone, the surface property is deteriorated and the obtained antistatic effect is not obtained. It deteriorates over time and is inferior in sustainability. Moreover, the antistatic effect is insufficient when only the fatty acid ester of sorbitan and / or its alkylene oxide adduct is added. Only by adding these two components to the SB block copolymer, excellent antistatic effect and antifogging property can be obtained.

The mixing weight ratio of the fatty acid ester of glycerin and the fatty acid ester of sorbitan and / or its alkylene oxide adduct used in the present invention is usually 5/9.
5 to 95/5, preferably 30/70 to 90/1
0, and more preferably 50/50 to 80/20.

The amount of the above mixture used is usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the SB block copolymer. If the amount used is too large, a sufficient antistatic effect cannot be obtained, and conversely the surface property is deteriorated, which is not preferable. If the addition amount is too small, sufficient antistatic effect and antifogging effect cannot be obtained.

The SB block copolymer composition of the present invention comprises
A mixture of a fatty acid ester of glycerin and a fatty acid ester of sorbitan and / or an alkylene oxide adduct thereof is mixed with powder or pellets of an SB block copolymer and directly molded by a method such as injection molding or extrusion molding. Alternatively, it may be produced by kneading the above-mentioned compound and molding into pellets as a molding material for injection molding, extrusion molding or the like.

When the styrene resin is blended and used, a master batch is prepared by kneading about 10% of a mixture of glycerin fatty acid ester and sorbitan fatty acid ester and / or its alkylene oxide adduct into the styrene resin. The composition of the present invention can be produced by producing and adding a predetermined amount of the SB block copolymer and the styrene resin during mixing and molding.

In addition, in the production of the styrene-based copolymer composition of the present invention, it is possible to add commonly used additives such as antioxidants, fillers, lubricants and pigments.

[0019]

The glycerin fatty acid ester, which has an antistatic effect but is inferior in surface properties and durability, and the sorbitan fatty acid ester and / or its alkylene oxide adduct, which has insufficient antistatic performance but is excellent in antifogging property And SB
When used in combination with a block copolymer, the synergistic effect of these two components suppresses bleeding of fatty acid ester of glycerin and aggregation over time on the resin surface, resulting in excellent antistatic and antifogging effects that have never been seen before. And is obtained.

[0020]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto.

Examples 1 to 6 and Comparative Examples 1 to 4 The butadiene content is 25% by weight and the styrene content is 75% by weight, and the block form is represented by the general formula {(SB) _n } _x C (where S is styrene). Block, B is a butadiene block, n is an integer of 1 to 5, C is a residue of a coupling agent,
x is the number of functional groups of this coupling agent and is an integer of 3 or more). A branched styrene-butadiene block copolymer (manufactured by Philips: trade name K-resin, K
R-03) 100 parts by weight of a commercially available additive shown in Table 1 (a high-purity type of glycerin fatty acid monoester is used) or an additive mixture is blended in a predetermined amount, and roll-kneaded at 155 ° C., Next, T- at 200 ° C
A 1 mm thick sheet was formed with a die / extruder. Each test piece thus obtained was left in a constant temperature and constant humidity test chamber at a temperature of 23 ° C. and a relative humidity of 50% to evaluate the antistatic performance and surface property.

[0022]

[Table 1]

The antistatic performance was evaluated by measuring the surface resistivity with a high resistance meter and the static voltage half-life with a static Honest meter (manufactured by Shishido Electrostatics Co., Ltd.). The surface property was evaluated by observing white turbidity and tackiness by visual observation, and evaluated it as good (good) and bad (bad). The results are shown in Table 2.

Examples 7 to 10 and Comparative Examples 5 to 7 Polystyrene resins (Mitsui Toatsu Chemicals, Inc .: trade name Topolex, 525-01) were blended with 10% by weight of each additive or additive mixture shown in Table 1. Then, it was pelletized using an extruder at 200 ° C. to prepare a masterbatch.
This masterbatch was blended in a blend resin in which the SB block copolymer used in Example 1 and the polystyrene resin were blended at a ratio of 7/3 (weight ratio) so that the addition amount shown in Table 2 was obtained. A test piece was prepared in the same manner as in Example 1, and the antistatic performance and surface property were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0025]

[Table 2]

Examples 11 to 15, Comparative Examples 8 to 10 To 100 parts by weight of the styrene-butadiene block copolymer (KR-03) used in Example 1, the additives or additive mixtures shown in Table 1 were respectively added. 155 in a prescribed amount
Roll kneading was carried out at 0 ° C, and then a sheet having a thickness of 0.3 mm was formed at 200 ° C with a T-die / extruder. Using each of the test sheets thus obtained, an antifogging test was conducted in the following procedure. Put warm water at 50 ℃ into a 400cc wide-mouth glass bottle, cover it with a sample sheet, attach the wide-mouth glass bottle to a constant temperature water tank adjusted to 50 ℃, and leave it in a constant temperature room at 25 ℃ for a predetermined time. The state of the film after the passage was observed and evaluated as high temperature antifogging property. Also, adjust the water temperature in the sample sheet to 20 ° C and leave it at an external temperature of 5 ° C for 2 hours.
It was evaluated as low temperature anti-fog property. The evaluation results are expressed according to the following criteria.

Evaluation Criterion 5: Completely transparent and free from fogging. 4: Almost transparent, but a slight amount of water drops. 3: Large water drops adhere, but there is a fairly transparent feeling. 2: Large water droplets are attached to the entire surface and it is opaque. 1: Fine water droplets are attached to the entire surface and are opaque. The evaluation results are shown in Table 3.

[0028]

[Table 3]

[0029]

INDUSTRIAL APPLICABILITY The styrene-butadiene block copolymer composition of the present invention has a good antistatic effect and antifogging effect without impairing surface properties, transparency and impact resistance. It can be widely used as a material.

Claims (6)

[Claims] 1. A styrene-butadiene block copolymer comprising a styrene-butadiene block copolymer and a mixture of a glycerin fatty acid ester and a sorbitan fatty acid ester and / or an alkylene oxide adduct thereof. Combined composition. 2. The styrene-butadiene block copolymer composition according to claim 1, wherein the mixing weight ratio of the fatty acid ester of glycerin and the fatty acid ester of sorbitan and / or its alkylene oxide adduct is 5/95 to 95/5. object. 3. A mixture of a fatty acid ester of glycerin and a fatty acid ester of sorbitan and / or an alkylene oxide adduct thereof is mixed in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of a styrene-butadiene block copolymer. The styrene-butadiene block copolymer composition according to 1 or 2. 4. A styrene-butadiene block copolymer containing 90% by weight or less of a styrene-based polymer.
Alternatively, the styrene-butadiene block copolymer composition described in 3 above. 5. The styrene-butadiene block copolymer composition according to claim 1, wherein the fatty acid ester of glycerin is glycerin monostearate. 6. The styrene-butadiene block copolymerization according to claim 1, wherein the sorbitan fatty acid ester and / or its alkylene oxide adduct is sorbitan monopalmitic acid ester and / or its alkylene oxide adduct. Combined composition.