Release agent for plastics and method for producing plastics for food container packaging

Abstract

To provide a release agent for plastics in the form of an organopolysiloxane emulsion having excellent storage stability, mechanical stability, wettability, and crack resistance, and with a low content of cyclic siloxane components of low polymerization degree, and a method for producing plastics for food container packaging employing the same.SOLUTION: The present invention provides a release agent for plastics and use thereof, characterized by being an emulsion having an average particle diameter of emulsion particles, as measured by a laser diffraction / scattering method, of more than 100 nm and 1,000 nm or less, the emulsion comprising: (A) 100 pts.mass of an organopolysiloxane having a kinematic viscosity at 25°C of 100 to 100,000 mm2 / s; (B) 0.1 to 18.0 pts.mass of an anionic surfactant; (C1) to (C3), three types of polyoxyethylene alkyl ethers having different contents (number of moles added) of oxyethylene units, each contained within a specific quantitative range; and (D) 35 to 100,000 pts.mass of water.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous silicone emulsion composition useful as a release agent for synthetic resin films or sheets (hereinafter referred to as films, etc.), and particularly to a release agent for plastics in the form of a silicone emulsion suitable for films for food packaging materials. Further, the present invention relates to a method for manufacturing plastics for food container packaging using the release agent for plastics.

Background Art

[0002] From the viewpoints of freshness and hygiene, foods are protected and sold in plastic trays, sheets, films, etc. As packaging materials for various food products, etc., thermoplastic resin films and sheets such as polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS) are widely used because of their excellent moldability and water resistance. Resin films, etc. are wound into rolls in their manufacturing process, and when used as packaging materials for food products, the rolled films, etc. are formed into cups or bags while being rewound. However, when a release agent is not used, the surfaces of the resin films, etc. adhere to each other, making it impossible to rewind smoothly, and there are problems such as deformation or breakage of the films, etc. when peeling. Also, when forming the container, problems such as adhesion to the mold and deterioration of the removability occur, and further, when punching and forming multiple stacked sheets, there are problems such as adhesion between products. Furthermore, molded products such as cases, trays, and cups formed from sheets and films are stored stacked, and if a release agent is not applied thereto, there is a problem of blocking.

[0003] As a means for solving these problems, the application of silicone release agents, particularly organopolysiloxane emulsions, is frequently used from the viewpoints of workability and safety. From the viewpoints of releasability and slipperiness, an emulsion composition of an organopolysiloxane having a kinematic viscosity at 25°C of 100 to 100,000 mm2 / s is suitable as a release agent for synthetic resins for food container packaging. (For example, Patent Document 1).

[0004] When applying an emulsion composition of organopolysiloxane as a release agent to plastics, dilute it with water so that the concentration of organopolysiloxane becomes 0.1 to 5.0% by mass, and apply it by rotary damping, gravure method or spray method.

[0005] In coating methods involving strong agitation such as rotary damping, the emulsion itself may be destroyed, leading to the occurrence of gel or oil floating. When applying the emulsion to plastics in a state where gel or oil floating has occurred, wetting unevenness occurs, resulting in problems such as adhesion between plastics and non-uniform appearance. Also, if the storage stability of the emulsion is poor, oil floating etc. may occur over time, causing wetting unevenness.

[0006] Also, when applying an emulsion of organopolysiloxane containing a large amount of nonionic surfactant to plastics, the nonionic surfactant may impregnate into the plastics, resulting in problems such as cracking and the formation of cracks in the molded body. Such cracks are likely to occur particularly in biaxially stretched polystyrene and polystyrene (PS) among plastics.

[0007] In recent years, octamethylcyclotetrasiloxane has become a candidate for substances of very high concern defined by the European REACH regulation and has come to be a concern as an environmental load substance. Therefore, products with a reduced content of octamethylcyclotetrasiloxane are in demand.

[0008] Therefore, there is a demand for an emulsion-type release agent of organopolysiloxane that is excellent in dilution stability, mechanical stability, storage stability, has good wettability, does not cause cracks in plastics, and has a low content of octamethylcyclotetrasiloxane.

[0009] In Japan, due to the amendment of the Food Sanitation Law, the "Positive List (PL) System for Food Utensils, Containers, and Packaging" has been implemented since June 1, 2020, and it is required to use only raw materials whose safety has been confirmed for food utensils, containers, and packaging. Also, regarding the coating agents used to manufacture plastic food utensils, containers, and packaging, conventionally, the Sanitary Council for Polyolefins and others has confirmed that they comply with the substances and restrictions listed in the Positive List and have passed the sanitary tests, and issued a certificate of confirmation. Since 2021, the Food Contact Materials Safety Center of the Chemical Research and Evaluation Institute, a general incorporated foundation, has taken over. Therefore, it is recommended to use raw material products whose safety has been confirmed for the use of containers and packaging that come into direct contact with food. For plastic release agents for food containers and packaging, an emulsion of organopolysiloxane that is safe and can solve the above-mentioned objective problems is desired.

[0010] Various methods have been studied to solve the above problems so far.

[0011] Patent Document 1 proposes a silicone release agent composition with less film whitening. The composition of Patent Document 1 contains propylene glycol. Also, in the examples, since emulsion polymerization is carried out using octamethylcyclotetrasiloxane as a raw material, there is a concern that 1% or more of octamethylcyclotetrasiloxane remains. Also, mechanical emulsification of organopolysiloxane is carried out, but polyoxyethylene lauryl ether is used alone as a nonionic emulsifier, and the average particle size does not become fine, and there is a possibility of poor stability. Also, among polyoxyethylene lauryl ethers, those with a polyoxyethylene chain of 1 to 6 may cause cracks in synthetic resins, especially PS and OPS. Therefore, there is a possibility of generating cracks when used as a release agent for PS and OPS even in the emulsion of the examples of Patent Document 1.

[0012] Patent Document 2 discloses an organopolysiloxane emulsion release agent composition that has excellent wettability and good transparency. However, in the examples, sodium polyoxyethylene nonylphenyl ether sulfate is used as an anionic surfactant, which is of concern as an environmentally hazardous substance, and therefore is not recommended for use as a release agent for plastics used in food container packaging.

[0013] The dimethylpolysiloxane release agent composition described in Patent Document 3 contains 500 ppm or less of dimethylsiloxane oligomers with 20 or less silicon atoms. In the examples, a polyoxyethylene (8.5 moles added) nonylphenyl ether emulsifier is used as the nonionic emulsifier, and a polyoxyethylene (3.5 moles added) octylphenol sulfate sodium salt emulsifier is used as the anionic surfactant. However, because these are considered to be environmentally hazardous substances, their use as a release agent for plastics used in food container packaging is not recommended.

[0014] Patent Document 4 relates to emulsions with a narrow particle size distribution and excellent stability, which are obtained by blending phenoxyethanols during emulsification, but the average particle size in the examples is large, at 1 μm or more, and it is expected that the dilution stability and mechanical stability will be poor. Furthermore, phenoxyethanol is not registered on the positive list.

[0015] Patent Document 5 is an alkylaralkyl co-modified silicone emulsion release agent for aluminum die casting. Alkylaralkyl co-modified silicone has lower release properties for plastics than dimethylpolysiloxane, and is therefore not suitable as a release agent for plastics.

[0016] Patent Document 6 discloses a silicone aqueous dispersion release agent composition using a sorbitan higher alkyl ester and other nonionic surfactants, which are preferably used during the vulcanization molding of acrylic rubber. In the silicone emulsion, when an anionic surfactant is blended, the negative value of the zeta potential of the emulsion increases, and the electrostatic repulsion between the emulsion particles becomes stronger, making it difficult to aggregate and improving the mechanical stability. Note that Patent Document 6 does not contain an anionic surfactant, and it is expected that the mechanical stability is low. Also, the silicone oil used in the examples is a polyether-modified silicone oil, and it is expected that the release property is insufficient.

[0017] Patent Document 7 discloses an emulsion in which an organopolysiloxane is emulsified with a polyoxyethylene alkyl ether having an HLB of 10 or more. Similar to Patent Document 6, there is no blending of an anionic surfactant, and it is expected that the mechanical stability is low. Also, there is a concern that a polyoxyethylene alkyl ether having an HLB of 10 or more may cause cracks when applied to plastics.

[0018] Patent Document 8 discloses a silicone emulsion composition comprising an organopolysiloxane, a polyoxyethylene alkyl ether having 8 to 11 carbon atoms in the alkyl chain, and an anionic surfactant. However, in an emulsion containing a polyoxyethylene alkyl ether having 8 to 11 carbon atoms, there is a risk of cracking when applied to plastics.

[0019] Patent Document 9 discloses a silicone emulsion composition in which an organopolysiloxane is emulsified with a polyoxyethylene alkyl ether and a sucrose fatty acid ester. In the examples thereof, polyoxyethylene(3) decyl ether is used as the polyoxyethylene alkyl ether, but a polyoxyethylene alkyl ether having 10 or less carbon atoms in the alkyl group may cause cracks in plastics.

[0020] Patent Document 10 discloses a silicone emulsion in which organopolysiloxane is emulsified with polyoxyethylene hexyldecyl ether or polyoxyethylene isostearyl ether. However, the average particle size in the examples is relatively large at about 400 nm, which may result in poor dilution stability and mechanical stability.

[0021] Patent Document 11 discloses an emulsion in which organopolysiloxane is emulsified with an anionic surfactant and a polyhydric alcohol. In general, anionic surfactants and polyhydric alcohols have a lower ability to lower surface tension than nonionic surfactants such as polyoxyethylene alkyl ethers. The emulsion in Patent Document 11 has a high surface tension (25°C) of 45 dyne / cm or more even when diluted 50 times with water. Furthermore, because it does not contain a nonionic surfactant, when applied to plastics, it has poor wetting properties and may cause cissing.

[0022] Patent Document 12 discloses an emulsion in which organopolysiloxane is used with polyoxyethylene alkyl ether or the like to reduce the particle size to 100 nm or less. However, since a large amount of polyoxyethylene alkyl ether is used to reduce the particle size of the emulsion to 100 nm or less, there is a risk of cracks occurring in plastics.

[0023] In contrast, Patent Document 13 proposes an emulsion with a particle size of 200 nm to 350 nm using an organopolysiloxane, an anionic surfactant, and a polyoxyethylene sorbitan fatty acid ester. However, the anionic surfactant and the polyoxyethylene sorbitan fatty acid ester have a weak effect of improving the stability of the organopolysiloxane emulsion, and there are concerns about the stability over time of the resulting emulsion composition, i.e., the mold release agent for plastics. In response to these technical problems, the applicants of this application proposed in Patent Document 14 a mold release agent for plastics in the form of an emulsion with excellent wettability and its use, but there was still room for further improvement in its performance and the stability of the emulsion itself. In addition, in these documents, there is no description or suggestion regarding a composition in which a plurality of specific polyoxyethylene alkyl ethers with different contents of oxyethylene units are used in a certain quantitative range / quantitative ratio and its technical significance and effects.

Prior Art Documents

Patent Documents

[0024]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

[0025] The present invention has been made to solve the above problems, and is safe, particularly excellent in storage stability and mechanical stability, has little repellency when applied to plastics, has good wettability, and is less likely to crack with respect to plastics. Preferably, it is an emulsion form of an organopolysiloxane having a low content of a cyclic siloxane component with a low degree of polymerization, and aims to provide a release agent for plastics and a method for producing a plastic for food container packaging using the same. [Means for Solving the Problems]

[0026] As a result of intensive studies on the above problems, the present inventors have reached the present invention. That is, the problems of the present invention are as follows: (A) an organopolysiloxane having a certain viscosity range, preferably having a low content of a cyclic siloxane with a low degree of polymerization: 100 parts by mass, (B) an anionic surfactant: 0.1 to 18.0 parts by mass, (C1) to (C3) three types of polyoxyethylene alkyl ethers having different contents (added mole numbers) of oxyethylene units are included in a specific quantitative range, and (D) water: 35 to 100,000 parts by mass, and the average particle diameter of the emulsion particles measured by the laser diffraction / scattering method exceeds 100 nm and is 1000 nm or less. The problems are solved by a release agent for plastics, its application to food packaging, and a method for producing a plastic for food container packaging using the release agent for plastics.

[0027] Specifically, the above problems are "[1] (A) Organopolysiloxane having a kinematic viscosity at 25 °C of 100 to 100,000 mm2 / s: 100 parts by mass, (B) Anionic surfactant: 0.1 to 18.0 parts by mass, (C1) The following general formula (2): C m H 2m+1 (OCH2CH2) n1 OH (2) (where m is a number from 10 to 20 and n1 is a number from 15 to 50.) Polyoxyethylene alkyl ether represented by: 0.2 to 15.0 parts by mass (C2) The following general formula (3): C m H 2m+1 (OCH2CH2) n2 OH (3) (where m is a number from 10 to 20 and n2 is a number from 6 to 14.) Polyoxyethylene alkyl ether represented by: 0.2 to 15.0 parts by mass (C3) The following general formula (4): C m H 2m+1 (OCH2CH2) n3 OH (4) (where m is a number from 10 to 20 and n3 is a number from 2 to 5.) Polyoxyethylene alkyl ether represented by: 0.2 to 15.0 parts by mass, The total amount of (C1), (C2), and (C3) is in the range of 0.6 to 20.0 parts by mass, , and (D) Water: 35 to 100,000 parts by mass containing, and an emulsion having an average particle diameter of emulsion particles measured by the laser diffraction / scattering method exceeding 100 nm and not exceeding 1000 nm, characterized as a mold release agent for plastics. The mold release agent for plastics according to [1], wherein the component (A) is an organopolysiloxane in which the contents of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane are each less than 1% by mass. [3] The component (A) is represented by the following general formula: [Chemical formula] (In the formula, R 1 may be the same or different and is any one of a hydroxy group, a hydrogen atom, an unsubstituted linear alkyl group having 1 to 32 carbon atoms, and a phenyl group, and L is an integer from 60 to 〖1,500).) The mold release agent for plastics according to claim 1, which is an organopolysiloxane represented by [4] The component (B) is one or more anionic surfactants selected from alkyl sulfate salts, alkyl sulfonate salts, alkylbenzene sulfonate salts, alkylnaphthalene sulfonate salts, alkyl sulfosuccinate salts, alkyl phosphate salts, polyoxyethylene alkyl ether sulfate ester salts, and polyoxyethylene alkyl ether phosphate ester salts. The mold release agent for plastics according to [1]. [5] Further, (E) the following general formula (5): [Chemical formula] (5) (R 2 is an alkyl group having 8 to 24 carbon atoms. a, b, and c are independently integers of 0 or more, and the sum of a + b + c is 8 to 30.) The mold release agent for plastics according to any one of [1] to [3], which contains 0.1 to 15.0 parts by mass of a polyoxyethylene sorbitan fatty acid ester represented by [6] The mold release agent for plastics according to [1], characterized in that when diluted with water so that the organopolysiloxane of the component (A) becomes 1.5% by mass, the surface tension is 35 mN / m or less. [7] The mold release agent for plastics according to any one of [1] to [6], characterized in that the plastic is for food container packaging. A method for manufacturing a plastic for food container packaging, using the mold release agent for plastic according to any one of [8][1] to [6]. is achieved by

[0028] In the mold release agent for plastic according to the present invention, the plastic is preferably a plastic for food container packaging, and particularly preferably a plastic sheet for food packaging (including films) or a molded product thereof.

Advantages of the Invention

[0029] According to the present invention, there is provided a mold release agent for plastic that has safety for use in food packaging, is particularly stable in emulsion itself over a long period of time, has excellent storage stability and mechanical stability, has little repellency when applied to plastic, has good wettability and dilution stability, and is less likely to cause stress cracks in plastic. More preferably, a mold release agent for plastic with a low content of volatile cyclic siloxane components (such as octamethylcyclotetrasiloxane) can be provided.

[0030] Furthermore, by using the mold release agent for plastic according to the present invention, there can be provided a method for manufacturing a plastic for food container packaging, which manufactures the above-mentioned plastic for food container packaging, particularly a plastic sheet for food packaging (including films) or a molded product thereof, by mold release or mold forming.

Best Mode for Carrying Out the Invention

[0031] Hereinafter, the mold release agent for plastic according to the present invention will be described in detail. The mold release agent for plastic contains the following components (A) to (D), and optionally may contain component (E) and other components within a range that does not impair the technical effects of the present invention. It is a mold release agent for plastic characterized in that it is an emulsion in which the average particle diameter of emulsion particles measured by the laser diffraction / scattering method exceeds 100 nm and is 1000 nm or less. The emulsion is in the form of an oil-in-water type organopolysiloxane emulsion with an aqueous phase as the continuous phase.

[0032] The mold release agent for plastics according to the present invention is characterized in that polyoxyethylene alkyl ethers having different contents of oxyethylene units, which are particularly components (C1), (C2), and (C3), are used in combination within a certain quantitative range. Compared with known mold release agents for plastics, the emulsion itself has excellent stability, particularly its storage stability and mechanical stability, and has the advantages of improved wettability and crack resistance of plastics and the like. By using these components (C1) to (C3) in combination, it is a great advantage of the present invention that all of the stability of the emulsion, wettability (coating property), and crack resistance of the resulting mold release coating layer can be achieved. On the other hand, if one of these components is missing or its quantitative range is exceeded, the technical effects of the present invention may not be achieved even if component (E) or the like is used in combination.

[0033] [(A) Organopolysiloxane] Component (A) is the main component of the silicone emulsion type mold release agent for plastics with water as the continuous phase according to the present invention, and is an organopolysiloxane (100 parts by mass) having a kinematic viscosity at 25°C of 100 to 100,000 mm2 / s. If the kinematic viscosity of component (A) is lower than 100 mm2 / s, the resulting composition may not exhibit sufficient mold release properties. On the other hand, if the kinematic viscosity of the organopolysiloxane of component (A) is greater than 100,000 mm2 / s, when applied to a film or the like, stickiness may occur on the surface. Also, if the kinematic viscosity of the organopolysiloxane is greater than 100,000 mm2 / s, emulsification becomes difficult and it is difficult to obtain an emulsion with good stability. Preferably, it is 200 to 50,000 mm2 / s, more preferably 300 to 30,000 mm2 / s, and even more preferably 500 to 20,000 mm2 / s.

[0034] The kinematic viscosity shall refer to the value of the kinematic viscosity at 25°C measured by a rotational viscometer conforming to JIS K7117-1. However, when the value of the kinematic viscosity exceeds 20,000 mm2 / s, the value obtained by dividing the viscosity value at 25°C measured by the single-cylinder rotational viscometer described in the above JIS standard by the measured value of the density at 25°C shall be adopted.

[0035] The organopolysiloxane of component (A) may have a kinematic viscosity at 25°C within the above range, and may be used alone or in combination of two or more.

[0036] It is preferable that the above (A) organopolysiloxane has a reduced content of low-polymerization cyclic siloxane components. Specifically, the contents of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane in component (A) are each less than 1% by mass, preferably each less than 0.5% by mass, and more preferably each less than 0.1% by mass. Particularly preferably, the contents of these low-polymerization cyclic siloxane components in component (A) are below the detection limit.

[0037] If the (A) organopolysiloxane contains a large amount of low-polymerization cyclic siloxane components, particularly octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane, it may be difficult to emulsify, or the average particle size may increase, or the storage stability, dilution stability, and mechanical stability may decrease, or cracks may easily occur during plastic coating. There are also concerns about environmental problems. The low-polymerization cyclic siloxane components in the (A) organopolysiloxane can be reduced by stripping, thin-film distillation equipment, etc.

[0038] Component (A) is preferably a linear organopolysiloxane, and particularly preferably an organopolysiloxane represented by the following general formula (1) and having a kinematic viscosity at 25°C of 100 to 100,000 mm2 / s. General formula: [Chemistry]

[0039] In formula (1), R 1 may be the same or different and is any one of an unsubstituted linear alkyl group having 1 to 32 carbon atoms, a phenyl group, a hydroxy group, and a hydrogen atom. Examples of the linear unsubstituted alkyl group having 1 to 32 carbon atoms include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group, and eicosyl group. R1 is preferably a linear unsubstituted alkyl group having 1 to 20 carbon atoms or a phenyl group, and more preferably a methyl group or a phenyl group from the viewpoint of versatility. Further, from the viewpoint of releasability, it is preferable that 50 mol% or more of the number of R1 in one molecule is a methyl group, and more preferably 75% or more is a methyl group. Further, L is an integer from 60 to 1,500, preferably from 150 to 1,200.

[0040] Such component (A) may industrially be dimethylpolysiloxane blocked at both molecular chain ends by trimethylsiloxy groups or hydroxydimethylsiloxy groups, and is preferable.

[0041] [(B) Anionic surfactant] Examples of the anionic surfactant as the component (B) include alkyl sulfate salts, polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, sulfate salts of fatty acid alkanolamides, alkyl sulfonates, polyoxyethylene alkyl phenyl ether sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl diphenyl ether disulfonates, alkane sulfonates, alkyl sulfosuccinates such as monoalkyl sulfosuccinates and dialkyl sulfosuccinates, polyoxyethylene alkyl ether sulfosuccinates, alkyl phosphates such as monoalkyl phosphate salts and dialkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, α-sulfo fatty acid ester salts, N-acyl taurates, fatty acid salts, polyoxyethylene alkyl ether carboxylates, N-acyl amino acid salts, etc. Examples of the salt include sodium salts, potassium salts, ammonium salts, triethanolamine salts, etc.

[0042] The amount of the anionic surfactant as the component (B), which is an emulsifier, is in the range of 0.1 to 18.0 parts by mass with respect to 100 parts by mass of the organopolysiloxane as the component (A). Preferably it is in the range of 0.15 to 15.0 parts by mass, more preferably in the range of 0.2 to 12.0 parts by mass, and still more preferably in the range of 0.25 parts by mass to 10.0 parts by mass. If the amount of the component (B) is less than 0.1 part by mass, the mechanical stability and dilution stability of the mold release agent for plastics of the present invention may decrease. On the other hand, if the amount of the component (B) is more than 18.0 parts by mass, the mold release property may decrease or the wettability to the substrate may decrease.

[0043] The anionic surfactant as the component (B) may be used alone or in combination of two or more.

[0044] [(C) Polyoxyethylene alkyl ether] (C1), (C2), and (C3) polyoxyethylene alkyl ethers are one of the characteristic configurations of the present invention. By using them in a specific quantitative range with the above-mentioned (A), (B) components, and (D) water, an emulsion with particularly excellent storage stability and mechanical stability can be formed, and there are advantages that the wettability of the resulting mold release agent for plastics and the crack resistance (= stress crack resistance) of plastics and the like are improved. In particular, only the anionic surfactant of the (B) component has a weak emulsifying power for the organopolysiloxane of the (A) component, and sufficient storage stability, mechanical stability, and dilution stability cannot be obtained. However, by blending a polyoxyethylene alkyl ether (C) with a specific structure in a specific quantitative range, the storage stability, mechanical stability, and dilution stability of the resulting mold release agent for plastics can be improved.

[0045] The three types of polyoxyethylene alkyl ethers ((C1) to (C3) components) that constitute the (C) component are different from each other in their structures, particularly in the content of oxyethylene units, and each component is added to the silicone emulsion-type mold release agent for plastics according to the present invention to achieve different technical effects. Hereinafter, the characteristics and technical significance of each component will be described.

[0046] The polyoxyethylene alkyl ether as the (C1) component has the following general formula (2): C m H 2m+1 (OCH2CH2) n1 OH (2) (m is a number from 10 to 20, and n1 is a number from 15 to 50.) It is represented by. The amount of polyoxyethylene alkyl ether as the component (C1) is 0.2 to 15.0 parts by mass with respect to 100 parts by mass of the organopolysiloxane as the component (A). In the mold release agent for plastics of the present invention, the component (C1) contributes mainly to the stabilization of the emulsion without impairing the crack resistance by being used within an appropriate blending amount range. When the blending amount of the component (C1) is less than 0.2 parts by mass, the stability of the emulsion obtained by emulsifying the organopolysiloxane as the component (A) may not be sufficiently improved. On the other hand, when it is more than 15.0 parts by mass, there is a risk of reducing the stability of the emulsion and a risk of cracks occurring when the mold release agent for plastics of the present invention is applied to plastics. A more preferable amount of use of the component (C1) is 0.25 to 10.0 parts by mass, and an even more preferable amount of use is 0.5 to 5.0 parts by mass.

[0047] The polyoxyethylene alkyl ether as the component (C1) preferably has an HLB of 15.0 to 19.5, and more preferably an HLB of 16.0 to 19.0, from the viewpoint of improving the stability of the emulsion. Here, HLB (hydrophilic-lipophilic balance) is the HLB of Griffin and is determined by the following formula: HLB = (molecular weight of hydrophilic group / total molecular weight) × (100 / 5) = {mass of hydrophilic group / (mass of hydrophobic group + mass of hydrophilic group)} × (100 / 5). In this specification, the same regulation is adopted for HLB.

[0048] In the above formula (2), m is the number of carbon atoms of the alkyl group, which is a number in the range of 10 to 20, may be a number in the range of 10 to 18, and may be a number in the range of 10 to 15. n1 is the number of added moles of oxyethylene units in the component (C1), which is a number in the range of 15 to 50, may be a number in the range of 18 to 40, and may be a number in the range of 19 to 30. In the formula (2) representing the component (C1), when it has an alkyl group with m in the range of 10 to 15, it is particularly preferable that n1 is a number in the range of 19 to 30, 19 to 27.

[0049] (C2) component polyoxyethylene alkyl ether is represented by the following general formula (3): C m H 2m+1 (OCH2CH2) n2 OH (3) (m is a number from 10 to 20, and n2 is a number from 6 to 14.) It is represented by. The usage amount of the polyoxyethylene alkyl ether as the (C2) component is 0.2 to 15.0 parts by mass with respect to 100 parts by mass of the organopolysiloxane as the (A) component. In the mold release agent for plastics of the present invention, the (C2) component contributes mainly to the stabilization of the emulsion and the wettability when the mold release agent for plastics of the present invention is applied to plastics within an appropriate blending amount range. If the blending amount of the (C2) component is less than 0.2 parts by mass, the stability of the emulsion obtained by emulsifying the organopolysiloxane as the (A) component may not be sufficiently improved, or the wettability with respect to the plastic substrate may decrease. On the other hand, if it is more than 15.0 parts by mass, cracks may occur when the mold release agent for plastics of the present invention is applied to plastics. A more preferable usage amount of the (C2) component is 0.25 to 10.0 parts by mass, and an even more preferable usage amount is 0.5 to 5.0 parts by mass.

[0050] (C2) component polyoxyethylene alkyl ether preferably has an HLB of 11.0 to 15.0, and more preferably an HLB of 11.5 to 14.5, from the viewpoints of improving the stability of the emulsion and the wettability with respect to the plastic substrate.

[0051] In the above formula (3), m is the number of carbon atoms of the alkyl group, which is the same number as described above. n2 is the added molar number of oxyethylene units in the (C2) component, which is a number in the range of 6 to 14, and may be a number in the range of 6 to 12, and may be a number in the range of 6 to 10. In the formula (3) representing the (C2) component, when it has an alkyl group with m in the range of 10 to 15, n2 is particularly preferably a number in the range of 6 to 10, 6 to 9, and may be 6.

[0052] (C3) component, polyoxyethylene alkyl ether, is represented by the following general formula (4): C m H 2m+1 (OCH2CH2) n3 OH (4) (m is a number from 10 to 20, and n3 is a number from 2 to 5.) It is represented by In the mold release agent for plastics of the present invention, the (C3) component, when used within an appropriate blending amount range, contributes to the improvement of wettability when the mold release agent for plastics of the present invention is applied to plastics. If the blending amount of the (C3) component is less than 0.2 parts by mass, the wettability to the plastic substrate may decrease. On the other hand, if it is more than 15.0 parts by mass, cracks may occur when the mold release agent for plastics of the present invention is applied to plastics. A more preferable usage amount of the (C3) component is 0.25 to 10.0 parts by mass, and an even more preferable usage amount is 0.5 to 5.0 parts by mass.

[0053] The polyoxyethylene alkyl ether, which is the (C3) component, preferably has an HLB of 5.0 to 11.0, and more preferably an HLB of 6.0 to 10.5, from the viewpoint of improving the wettability to the plastic substrate.

[0054] In the above formula (4), m is the number of carbon atoms of the alkyl group, which is the same number as described above. n3 is the number of added moles of oxyethylene units in the (C3) component, which is a number in the range of 2 to 5, and may be a number in the range of 3 to 5. In the formula (4) representing the (C3) component, when it has an alkyl group with m in the range of 10 to 15, it is particularly preferable that n3 is a number in the range of 3 to 5, and it may be 4.

[0055] The amount of polyoxyethylene alkyl ether, which is the component (C1), (C2), or (C3), is 0.6 to 20.0 parts by mass in total as the components (C1), (C2), and (C3) with respect to 100 parts by mass of the organopolysiloxane, which is the component (A). When the total amount of the components (C1) to (C3) is less than 0.6 parts by mass, the stability of the emulsion obtained by emulsifying the organopolysiloxane, which is the component (A), may not be sufficiently improved. On the other hand, when the total amount of the components (C1) to (C3) is more than 20.0 parts by mass, cracks may occur when the mold release agent for plastics of the present invention is applied to plastics. The more preferable total amount of the components (C1), (C2), and (C3) used is 1.0 to 15.0 parts by mass, and the further preferable amount used is 3.0 to 12.0 parts by mass.

[0056] Specific examples of the component (C) (specific examples of polyoxyethylene alkyl ethers having different numbers of added moles of polyoxyethylene (POE)) include polyoxyethylene linear alkyl ethers such as polyoxydecyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene hexyl decyl ether, polyoxyethylene isostearyl ether, and polyoxyethylene octyl dodecyl ether; polyoxyalkylene branched primary alkyl ethers such as polyoxyethylene 2-ethylhexyl ether, polyoxyethylene isocetyl ether, and polyoxyethylene isostearyl ether; and polyoxyalkylene branched secondary alkyl ethers such as polyoxyethylene 1-hexylhexyl ether, polyoxyethylene 1-octylhexyl ether, polyoxyethylene 1-hexyloctyl ether, polyoxyethylene 1-pentylheptyl ether, and polyoxyethylene 1-heptylpentyl ether, but are not limited thereto.

[0057] [(D) Water] The mold release agent for plastics of the present invention is an emulsion composition of organopolysiloxane, and is in the form of an oil-in-water emulsion (i.e., silicone emulsion) characterized in that (D) water is used as the dispersion medium (= continuous phase).

[0058] (D) The amount of water used as a component is 35 to 100,000 parts by mass with respect to 100 parts by mass of the organopolysiloxane as the (A) component. Preferably, it is 50 to 20,000 parts by mass. When (D) water is less than 35 parts by mass, stickiness, coating unevenness, and cracks may occur when the mold release agent for plastics of the present invention is applied to plastics. In addition, the viscosity of the emulsion composition becomes high, which is not preferable. On the other hand, when (D) water is more than 100,000 parts by mass, the mechanical stability decreases, and oil floating or the like may occur after dilution and stirring. In addition, when the dilution ratio is high, the amount of the emulsion composition required to exhibit the effect as a mold release agent increases, resulting in an economically unfavorable situation.

[0059] [(E) Polyoxyethylene sorbitan fatty acid ester] Optionally, the mold release agent for plastics according to the present invention may further contain, as the (E) component, 0.1 to 15.0 parts by mass of a polyoxyethylene sorbitan fatty acid ester represented by the following general formula (5). [Chemical formula] (5) (R 2 is an alkyl group having 8 to 24 carbon atoms. a, b, and c are independently integers of 0 or more, and the sum of a + b + c is 8 to 30.)

[0060] In formula (2), when the sum of a + b + c is less than 8, the emulsifying property may be insufficient and the stability may be poor. On the other hand, when the sum of + b + c is greater than 30, the viscosity may be high or it may become solid, resulting in a decrease in handling workability.

[0061] (E) The polyoxyethylene sorbitan fatty acid ester may be used alone or in combination of two or more. The HLB of the polyoxyethylene sorbitan fatty acid ester as component (E) can be 10 to 18, preferably 12 to 18. If the HLB of component (E) is within these ranges, the emulsifying power is good, and when used in combination with the above-mentioned (B) and a predetermined component (C) (components (C1) to (C3)), a plastic release agent with further improved stability may be obtained.

[0062] The amount of the polyoxyethylene sorbitan fatty acid ester as component (E) is 0.1 to 15.0 parts by mass with respect to 100 parts by mass of the organopolysiloxane as component (A). Preferably it is 0.2 to 13.0 parts by mass, more preferably 0.5 to 11.0 parts by mass. If the blending amount of component (E) is less than 0.1 part by mass, the stability of the emulsion obtained by emulsifying the organopolysiloxane as component (A) may not be sufficiently improved. On the other hand, if it is more than 15.0 parts by mass, there is a risk of cracks occurring when the plastic release agent of the present invention is applied to plastic.

[0063] [Other components] The plastic release agent of the present invention may contain a water-soluble polymer for the purpose of improving the dispersibility of the organopolysiloxane as component (A). The water-soluble polymer compound is not particularly limited, and examples include nonionic water-soluble polymer compounds, anionic water-soluble polymer compounds, cationic water-soluble polymer compounds, and amphoteric water-soluble polymer compounds.

[0064] Examples of nonionic water-soluble polymer compounds include polymers of vinyl alcohol, copolymers of vinyl alcohol and vinyl acetate, polymers of acrylamide, polymers of vinyl pyrrolidone, copolymers of vinyl pyrrolidone and vinyl acetate, polyethylene glycol, polymers of isopropylacrylamide, polymers of methyl vinyl ether, starch, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, guar gum, xanthan gum, and the like.

[0065] Examples of anionic water-soluble polymer compounds include polymers of sodium acrylate, copolymers of sodium acrylate and sodium maleate, copolymers of sodium acrylate and acrylamide, polymers of sodium styrene sulfonate, copolymers of sodium polyisoprene sulfonate and styrene, polymers of sodium naphthalene sulfonate, carboxymethyl starch, phosphate starch, carboxymethyl cellulose, sodium alginate, gum arabic, carrageenan, sodium chondroitin sulfate, sodium hyaluronate, and the like.

[0066] Examples of cationic water-soluble polymer compounds include polymers of dimethyldiallylammonium chloride, polymers of vinylimidazoline, polymers of methylvinylimidazolium chloride, polymers of ethyl acrylate trimethylammonium chloride, polymers of ethyl methacrylate trimethylammonium chloride, polymers of acrylamidepropyltrimethylammonium chloride, polymers of methacrylamidepropyltrimethylammonium chloride, epichlorohydrin / dimethylamine polymers, polymers of ethyleneimine, quaternized products of polymers of ethyleneimine, polymers of allylamine hydrochloride, polylysine, cationic starch, cationized cellulose, chitosan, and derivatives thereof obtained by copolymerizing monomers having nonionic groups or anionic groups with these, and the like.

[0067] Examples of amphoteric water-soluble polymer compounds include copolymers of ethyl acrylate trimethylammonium chloride, acrylic acid, and acrylamide, copolymers of ethyl methacrylate trimethylammonium chloride, acrylic acid, and acrylamide, Hofmann degradation products of polymers of acrylamide, and the like.

[0068] The mold release agent for plastics of the present invention may contain an antibacterial and antifungal agent or an antibacterial agent. Examples of the antibacterial and antifungal agent include alkyl p - hydroxybenzoate, benzoic acid, sodium benzoate, sorbic acid, potassium sorbate, phenoxyethanol, isothiazolinone derivatives, etc. Examples of the antibacterial agent include benzoic acid, salicylic acid, phenol, sorbic acid, alkyl p - hydroxybenzoate, p - chloro - m - cresol, hexachlorophene, benzalkonium chloride, chlorhexidine chloride, trichlorocarbanilide, photosensitizer, phenoxyethanol, etc. In addition, a pH adjuster, an anti - fogging agent, a fragrance, an antioxidant, a rust inhibitor, a dye, a filler, a curing catalyst, an organic powder, an inorganic powder, an anti - blocking agent, an antistatic agent, a viscosity modifier, an antifoaming agent, an ultraviolet absorber, a coloring inhibitor, etc. may also be blended.

[0069] [Preparation of Composition] The mold release agent for plastics of the present invention can be obtained in the form of an oil - in - water emulsion by emulsifying (A) organopolysiloxane in (D) water using (B) an anionic surfactant and a predetermined polyoxyethylene alkyl ether composed of a combination of components (C1) to (C3), and optionally (E) polyoxyethylene sorbitan fatty acid ester. Hereinafter, the "particle size" or "grain size" means the average particle size of the emulsion particles measured by the laser diffraction / scattering method.

[0070] Emulsification may be carried out using a general emulsifying and dispersing machine. Examples of the emulsifying and dispersing machine include high - speed rotating centrifugal spraying type stirrers such as homodispersers, high - speed rotating shearing type stirrers such as homomixers, high - pressure jet type emulsifying and dispersing machines such as pressure - type homogenizers, colloid mills, combimixers, in - line continuous emulsifiers, vacuum emulsifiers, continuous mixing devices, ultrasonic emulsifiers, etc.

[0071] Regarding the temperature during emulsification, it is preferably 0 to 80°C, more preferably 10 to 60°C. At a temperature of 10°C to 80°C, emulsification is easier, and the produced emulsion tends to be more stable. When emulsifying, the pressure may be not only normal pressure but also reduced pressure or increased pressure. When emulsifying under reduced pressure or increased pressure, it may be difficult for bubbles to mix in and emulsification can be effectively carried out. When reducing the pressure, the pressure is preferably higher than the vapor pressure of the raw materials so that the raw materials do not volatilize. In addition, when using a batch-type emulsifying device, the emulsification time is not particularly specified and may be the time when the target particle size is achieved, but generally it is preferably 360 minutes or less.

[0072] The average particle size of the mold release agent for plastics of the present invention exceeds 100 nm and is 1000 nm or less. Preferably, it exceeds 200 nm and is 800 nm or less. If the average particle size is larger than 1000 nm, the dilution stability and mechanical stability will decrease, and oil floating and the like may occur during dilution and stirring. In addition, when stored for a long time, there may be a risk of shade separation. On the other hand, in order to produce an emulsion with an average particle size of 100 nm or less, generally, the content of nonionic surfactants typified by a predetermined polyoxyethylene alkyl ether or (E) polyoxyethylene sorbitan fatty acid ester, which is a combination of component (C): components (C1) to (C3), with respect to (A) organopolysiloxane, tends to increase. Therefore, when the components (C) and (E) are used within the quantitative range of the present invention, it is difficult to achieve an emulsion particle size of 100 nm or less. Also, when the components (C) and (E) are blended beyond the scope of the present invention, the mold release property may decrease and cracks may occur when coated on plastics.

[0073] [Use of the mold release agent for plastics and manufacturing method of plastics for food container packaging] The emulsion obtained as described above is extremely useful as a mold release agent for plastic sheets for food packaging, molded articles thereof, etc., and also as a mold release agent used during mold forming. For example, the mold release agent for plastics of the present invention in which the content of component (A) is 0.1 to 2.0% by mass can be applied by known methods such as spray coater, roll coater, gravure roll coater, knife coater, air knife coater, rotor dump coating coater, applicator method, etc., and there are no particular limitations. The coating amount is generally 0.01 to 1.0 g / m2 on a dry basis, and particularly preferably 0.02 to 0.2 g / m2. If it is 0.01 g / m2 or more, sufficient mold release properties can be obtained, and if it is 1.0 g / m2 or less, it is preferable from the viewpoints of transparency and stickiness.

[0074] Examples of plastics for food container packaging include polyethylene, polypropylene, polymethylpentene, polybutene, ethylene-tetracyclododecene copolymer, ethylene-2-norbornene copolymer, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer, polyphenylene ether, polyacrylonitrile, polymethacrylstyrene, polymethyl methacrylate, nylon, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyacetal, polybutylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene naphthalate, and polyvinyl chloride, etc.

[0075] Preferred resin sheets can be sheets having moldability, particularly hydrophobic synthetic resin sheets, for example, olefin resins (particularly polypropylene resins), polyester resins (particularly polyethylene terephthalate resins), and styrene resins. Styrene resins can include homopolymers containing aromatic vinyl monomers (styrene, vinyltoluene, α-methylstyrene, etc.) as constituent components, copolymers of aromatic vinyl monomers and copolymerizable monomers, and mixtures thereof. More specifically, examples of styrene resins include non-rubber-reinforced styrene resins [general-purpose polystyrene (GPPS), styrene-methyl methacrylate copolymer (MS resin), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-styrene-methyl methacrylate copolymer, etc.], rubber-containing styrene resins [rubber-reinforced polystyrene (high-impact polystyrene: HIPS), styrene-diene block copolymer or its hydrogenated product (such as polystyrene-polybutadiene-polystyrene block copolymer), acrylonitrile-butadiene-styrene copolymer (ABS resin), AXS resin in which acrylonitrile A and styrene S are graft-polymerized onto rubber component X (acrylic rubber, chlorinated polyethylene, ethylene-propylene rubber (EPDM), ethylene-vinyl acetate copolymer, etc.)]. These styrene resins can be used alone or in a mixture of two or more. Note that the styrene resin sheet can be a highly transparent styrene resin sheet (for example, a non-rubber-reinforced styrene resin sheet composed of a non-rubber-reinforced styrene resin such as GPPS, a styrene resin sheet composed of a styrene resin and a styrene-diene block copolymer or its hydrogenated product), or a rubber-reinforced styrene resin sheet.

[0076] According to the present invention, by emulsifying organopolysiloxane in water using an anionic surfactant, polyoxyethylene alkyl ether, and, if necessary, polyoxyethylene sorbitan fatty acid ester, a mold release agent for plastics can be provided that has excellent mold release properties, good dilution stability, mechanical stability, storage stability, wettability, and is less likely to cause stress cracking.

[0077] Furthermore, a method for manufacturing plastics for food container packaging, which is characterized by the use of the mold release agent for plastics of the present invention, can be provided. Specifically, by using the mold release agent for plastics according to the present invention, a method for manufacturing plastics for food container packaging, in particular, plastic sheets (including films) for food packaging and molded articles thereof, etc., can be manufactured by mold release or mold forming.

[0078] The method for manufacturing plastics for food container packaging is as follows: Step (I): A step of applying the mold release agent for plastics of the present invention to a mold or the like by spraying or the like; Step (II): A step of molding plastics for food container packaging; and Step (III): A step of releasing the molded plastics for food container packaging. It comprises the above steps, and the coating method, coating amount, and types of plastics that can be used are as described above.

[0079] [Use of anti-fog agent] For the plastics for food container packaging of the present invention, an anti-fog agent in the form of an aqueous solution or the like can be applied to at least one surface of a thermoplastic resin sheet obtained by forming a thermoplastic resin by a known method. When treating the other surface without the mold release agent for plastics with an anti-fog agent, after performing a hydrophilic treatment, the anti-fog agent is applied to this treated surface, and the solvent is dried to form an anti-fog layer. Also, an anti-fog agent may be blended into the mold release agent for plastics of the present invention itself, or it can be mixed and blended into the mold release agent for plastics. It is also possible to mix it with the raw materials of the mold release agent for plastics before emulsification and then perform an emulsification treatment for blending.

[0080] As the method for applying the anti-fog agent, known methods such as spray coater, roll coater, gravure roll coater, knife coater, air knife coater, rotor dump coating coater, applicator method, etc. can be mentioned, and there is no particular limitation.

[0081] As the anti-fogging agent, known surfactants can be used, such as polyhydric alcohol type nonionic surfactants (glycerol fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, pentaerythritol fatty acid esters, trimethylolpropane fatty acid esters, polyglycerol fatty acid esters, polyoxyethylene glycerol fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyoxyethylene aliphatic alcohol ethers, etc.), water-soluble polymers (polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyoxyethylene polyoxypropylene block copolymers, hydrophilic acrylic copolymers, etc.), and polysaccharides (starch, phytoglycogen, fructan, galactomannan, glucomannan, mannan, barley and oat glucan, cellulose, hemicellulose, β-1,3-glucan, galactan, arabinan, xylan, arabogalactan, araboxylan, araboglucan, pectin, gum arabic, tragacanth gum, locust bean gum, guar gum, mesquite gum, carrageenan, glucuronoxylan, laminaran, inulin, lichenin, fructosan, chitin, chitosan, alginic acid or its salts (such as sodium alginate), hyaluronic acid, chondroitin sulfate, caronin sulfate, gelatin, agar, fucidin, trollius, curdlan, xanthan gum, pullulan, dextran, cyclodextrin, nigeran, levan, etc.). A mixture of two or more of these is particularly preferred. When applying these, corona treatment is performed, and it is preferable to make the contact angle with water on the sheet surface 20° to 80°.

[0082] [Replacement of known products] The mold release agent for plastics according to the present invention can replace some or all of known or commercially available emulsion-type plastic mold release agents, particularly those used for food packaging applications. As an example, it can be used without limitation in the same applications as DOWSIL(TM) SM 7025 EX Emulsion, which is commercially available from The Dow Chemical Company - Toray Silicone Co., Ltd. as a mold release agent for plastics including food packaging applications. The coating method, applications, target products, etc. at that time may be those described in the technical materials of the above products and may be the same as those of known or commercially available products. However, by using the mold release agent for plastics according to the present invention instead of commercially available products in common use, there are advantages such as reducing the content of low-polymerization cyclic siloxane components, which are favorable characteristics of the product, and achieving technical improvements such as crack resistance. However, it goes without saying that the applications of the mold release agent for plastics according to the present invention are not limited to replacing known products.

Examples

[0083] Hereinafter, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to the following examples.

[0084] The components used in the following examples and comparative examples are as follows.

[0085] [Component (A) and comparative organopolysiloxane] (A1) Organopolysiloxane: Represented by the following general formula (4), the kinematic viscosity at 25°C is 9970 mm2 / s, L1 is 580, and the contents of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane are each 100 ppm or less.

Chemical formula

[0086] [Component (B)] (B-1) 40% Aqueous solution of sodium alkanesulfonate (Trade name: Latemul PS, manufactured by Kao Corporation), (B-2) 70% Aqueous solution of sodium dioctyl sulfosuccinate (Trade name: Perex OT-P, manufactured by Kao Corporation), (B-3) 65% Aqueous solution of sodium dodecylbenzenesulfonate (Trade name: Neoperex G-65, manufactured by Kao Corporation), (B-4) Sodium lauryl sulfate (Trade name: Emal 2FG, manufactured by Kao Corporation)

[0087] [Component (C)] (C1) Polyoxyethylene (23 moles) lauryl ether (Trade name: Emulgen 123P, C 12 H 25 (OCH2CH2) 23 OH, HLB = 16.9, manufactured by Kao Corporation), (C2) Polyoxyethylene (6 moles) lauryl ether (Trade name: Emulgen 108P, C 12 H 25 (OCH2CH2)6OH, HLB = 12.1, manufactured by Kao Corporation), (C3) Polyoxyethylene (4 moles) lauryl ether (Trade name: Emulgen 104P, C 12 H 25 (OCH2CH2)4OH, HLB = 9.6, manufactured by Kao Corporation)

[0088] [Component (D)] (D) Water

[0089] [Component (E)] Polyoxyethylene sorbitan monooleate (Trade name: Leodol TW-O120V, manufactured by Kao Corporation)

[0090] [Other emulsifiers] Polyoxyethylene-polyoxypropylene copolymer type nonionic emulsifier (Trade name: Pluronic (registered trademark) F108, manufactured by Adeka Corporation)

[0091] [Other components] Sodium benzoate, methyl p-hydroxybenzoate, propyl p-hydroxybenzoate, citric acid

[0092] [Example 1] 2 parts by mass of an anionic surfactant, 0.5 part by mass of polyoxyethylene (23 mol) lauryl ether (C1), 0.5 part by mass of polyoxyethylene (6 mol) lauryl ether (C2), 0.5 part by mass of polyoxyethylene (4 mol) lauryl ether (C3), 3.1 parts by mass of polyoxyethylene sorbitan monooleate (E), 0.1 part by mass of methyl p-hydroxybenzoate, 0.03 part by mass of propyl p-hydroxybenzoate and 1.5 parts by weight of water (D) were mixed in advance and placed in a container containing 30.0 parts by mass of an organopolysiloxane (A), and emulsified using an emulsifier. To the obtained emulsion, 0.5 part by mass of sodium benzoate and the balance of water (D) were added and diluted, and stirred until uniform to prepare a mold release agent for plastics according to Example 1 (in the form of an emulsion composition).

[0093] [Examples 2 to 6, Comparative Examples 1 to 8] In the same procedure as in Example 1, mold release agents for plastics according to Examples 2 to 6 and Comparative Examples 1 to 8 (all in the form of emulsion compositions) were prepared with the compositions shown in Table 1. In Table 1, "parts" means parts by mass.

[0094]

Table 1

[0095] Hereinafter, the mold release agents for plastics of Examples 1 to 6 and Comparative Examples 1 to 8 were evaluated for average particle size, pH, storage stability, wettability with respect to the film, and stress cracking with respect to the film. Details of the evaluation methods are described below.

[0096] [Average Particle Size] Using water as the dispersion medium, the particle size of the silicone emulsion was measured with a laser diffraction particle size distribution analyzer (Mastersizer 3000 manufactured by Malvern Panalytical), and the value of the median diameter (the particle size corresponding to 50% of the cumulative distribution) was obtained.

[0097] [Storage Stability] Each mold release agent for plastics was placed in a glass bottle with a capacity of about 100 mL and stored at 25°C, and water separation, oil separation, and creaming were evaluated. The evaluation was based on the following criteria. 〇: No separation for more than 3 months. △: No separation for 1 month. ×: Separation within 1 week. ××: Separation within 1 day.

[0098] [Surface Tension] It was diluted with water so that the silicone content was 1.5%, and the surface tension was measured by the ring method (K12 of KRUSS) using a platinum ring. [Wettability] Each mold release agent for plastics was applied to a PET film (Lumirror (R) 60 manufactured by Toray Industries, Inc.) using a Meyer bar No. 3. The presence or absence of repulsion was visually confirmed. ○: It wets the whole. △: Repulsion occurs in part. ×: Repulsion occurs in the whole immediately after coating. In this specification, "○" and "△" are judged as good, and "×" is judged as bad.

[0099] [Crack Resistance] 10 g of the above emulsion composition was put into a 30 cc glass bottle, and a 2.5 cm × 6 cm OPS sheet (=biaxially stretched polystyrene sheet, Santoclear SP manufactured by Mitsubishi Chemical Corporation) was rolled up and immersed. After being placed in an oven at 50°C for 7 hours, the presence or absence of cracks was visually confirmed. "○" was judged as good and "×" as bad.

[0100] The evaluation results of the mold release agents for plastics according to Examples 1 to 6 and Comparative Examples 1 to 9 are shown in Table 2 below.

Table 2

[0101] In Comparative Examples 1 to 9 lacking the (C1, C2, C3) components of the present invention, any one of crack resistance, storage stability, and wettability becomes poor. Therefore, the mold release agent for plastics of the present invention has a clear performance superiority over the known technology, and in particular, it is expected that sufficient technical benefits can be realized by using it in the production of plastics for food container packaging.

Claims

1. (A) An organopolysiloxane having a kinematic viscosity at 25°C of 100 to 100,000 mm2 / s: 100 parts by mass, (B) An anionic surfactant: 0.1 to 18.0 parts by mass, (C1) The following general formula (2): C ｍ H ２ｍ＋１ (OCH ２ CH ２ ) ｎ１ OH (2) (m is a number from 10 to 20, and n1 is a number from 15 to 50.) A polyoxyethylene alkyl ether represented by: 0.2 to 15.0 parts by mass (C2) The following general formula (3): C ｍ H ２ｍ＋１ (OCH ２ CH ２ ) ｎ２ OH (3) (m is a number from 10 to 20, and n2 is a number from 6 to 14.) A polyoxyethylene alkyl ether represented by: 0.2 to 15.0 parts by mass (C3) The following general formula (4): C ｍ H ２ｍ＋１ (OCH ２ CH ２ ) ｎ３ OH (4) (m is a number from 10 to 20, and n3 is a number from 2 to 5.) A polyoxyethylene alkyl ether represented by: 0.2 to 15.0 parts by mass, The total amount of (C1), (C2), and (C3) is in the range of 0.6 to 20.0 parts by mass, and (D) Water: 35 to 100,000 parts by mass A mold release agent for plastics, characterized in that it contains the above components and is an emulsion having an average particle diameter of the emulsion particles measured by the laser diffraction / scattering method exceeding 100 nm and being 1000 nm or less.

2. The mold release agent for plastics according to Claim 1, wherein the component (A) is an organopolysiloxane in which the contents of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane are each less than 1% by mass.

3. The mold release agent for plastics according to Claim 1, wherein the component (A) is an organopolysiloxane represented by the following general formula: 【Chemical 1】 (wherein R １ may be the same or different and is any one of a hydroxy group, a hydrogen atom, an unsubstituted linear alkyl group having 1 to 32 carbon atoms, and a phenyl group, and L is an integer from 60 to 1,500.)

4. The mold release agent for plastics according to Claim 1, wherein the component (B) is one or more anionic surfactants selected from alkyl sulfate salts, alkyl sulfonate salts, alkylbenzene sulfonate salts, alkylnaphthalene sulfonate salts, alkyl sulfosuccinate salts, alkyl phosphate salts, polyoxyethylene alkyl ether sulfate ester salts, and polyoxyethylene alkyl ether phosphate ester salts.

5. Further, (E) A polyoxyethylene sorbitan fatty acid ester represented by the following general formula (5): 0.1 to 15.0 parts by mass is included. The mold release agent for plastics according to any one of Claims 1 to 3. [Chemical Formula 2] （５） (R ２ is an alkyl group having 8 to 24 carbon atoms. a, b, and c are independently integers of 0 or more, and the sum of a + b + c is 8 to 30.)

6. The mold release agent for plastics according to Claim 1, characterized in that when diluted with water so that the organopolysiloxane of the component (A) becomes 1.5% by mass, the surface tension is 35 mN / m or less.

7. The mold release agent for plastic according to any one of claims 1 to 6, wherein the plastic is for food container packaging.

8. A method for manufacturing a plastic for food container packaging, using the mold release agent for plastic according to any one of claims 1 to 6.

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