KR20070071803A - Silicone composition for molded semi-rigid foam - Google Patents

Abstract

Provided is a silicone composition for a mold semi-rigid foam capable of inhibiting the generation of pin hole, void or coarse cell on the surface of a urethane foam in case of de-molding and preventing the generation of scale. The silicone composition comprises: 5-20 wt% of a silicone resin which has a number average molecular weight of 1,000-10,000 and a ratio of an M unit and a Q unit of 0.1 : 1 or 1.3 : 1 and is represented by the formula(1); 73-90 wt% of a cyclopolysiloxane which has a number average molecular weight of 100-10,000 and has a repeating unit represented by -Si-O-Si-; and 2-10 wt% of an organic silane containing an alkoxy group represented by -OR5, wherein R is OH, H, a 6 to 12-membered aromatic ring, a C1-C12 alkyl group, a C1-C12 alkoxy group, or COOR3; R3 is a C1-C12 alkyl group or a 6 to 12-membered aromatic ring; and R5 is H, a C1-C12 alkyl group, a C2-C12 alkenyl group, or a 6 to 12-membered aromatic ring.

Description

Silicone composition for mold semi-rigid foam {SILICONE COMPOSITION FOR MOLDED SEMI-RIGID FOAM}

Semi-rigid polyurethane foam usually shows the median compressive strength and hardness of soft foam and rigid foam, and is 0.15 ~ 1.0 g / cm ³ Widely used in applications that use impact energy absorbency in density. Such semi-rigid polyurethane foams are mainly used in the field of automotive interiors, depending on their use, Molded Semi-Rigid Form (MSF), Integral Skin Foam (ISF), and Reaction Injection Molding ( Reaction Injection Molding (RM).

Instrument panel, instrument air bag cover, arm rest, head rest, console box, glove box, etc. Corresponds to the semi-rigid foam. Molded semi-rigid foam is generally molded to facilitate demoulding from a mold by injecting a stock solution containing a resin premix, isocyanate, etc. into a mold of a predetermined shape and forming a product in a mold shape. A release agent is applied to the mold.

As the mold release agent for semi-rigid foams, in general, higher fatty acids, higher fatty acid soaps, waxes, animal fats, and the like have been used, but these materials have a disadvantage of low releasability and low heat resistance. Thus, polydimethylsiloxane has recently been used. Was done. Polydimethylsiloxane is colorless, transparent, almost nontoxic, has excellent thermal stability, no adhesion due to thermal decomposition, and smooth surface due to low surface tension, so that it is easy to apply even to fine scratches, but it is a conventional product using such polydimethylsiloxane. Has the following problems.

(1) In the case of using polydimethylsiloxane itself, there is a release property, but there is a disadvantage that can greatly inhibit the paintability of the molded foam after demolding (Reference: 2002 New Technology Trend Report-Silicone Polymer, Korea Intellectual Property Office).

(2) Alkyl-modified polysiloxanes can exhibit excellent lubricity in the low temperature range, but are not easily released at high temperatures of 200 ° C. or higher (CA 2,183,299).

(3) When a silicone mixture containing methylphenylpolysiloxane and alkyl-modified polysiloxane is used as an aqueous emulsion release agent using an emulsifier and water as a solvent, the releasability is poor due to the hydroxyl groups remaining during molding of the plastic foam (see: JP90 -12,886).

In addition, a conventional release agent is a pinhole phenomenon in which bubbles are formed on the surface of a molded foam when demolding, a void phenomenon in which crater-shaped pores occur on the surface of a manufactured foam, or a rough surface cell of a foam. A coarse cell phenomenon may appear.

The present invention for solving the above problems suppresses the phenomenon of pin holes, voids, coarse cells, etc. appearing on the surface of the urethane molding foam when demolding, and the scale after the molding ( It is an object of the present invention to provide a release composition for a semi-rigid foam because it prevents the occurrence of scale) to prevent yellowing of the skin of the urethane foam, and has excellent release property compared to the conventional release agent.

The present invention (A) 5 to 20% by weight of a silicone resin having a structure of the formula (1) having a number average molecular weight of 1,000 to 10,000, the ratio of M unit and Q unit of 0.1: 1 to 1.3: 1;

(B) 73 to 90% by weight of cyclopolysiloxane of the -Si-O-Si- repeating unit structure having a number average molecular weight of 100 to 10,000; And

(C) an organosilane 2 containing an alkoxy group (-OR ₅ , wherein R ₅ represents H, C ₁ -C ₁₂ alkyl, C ₂ -C ₁₂ alkenyl, or an aromatic ring having 6 to 12 ring members) It relates to a silicone composition comprising from 10% by weight.

Where

R is a hydroxy group, hydrogen, an aromatic ring having 6 to 12 ring members, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, or COOR ₃ Wherein R ₃ is C ₁ -C ₁₂ alkyl or an aromatic ring having 6 to 12 ring members.

 In the following, the silicone composition for a semi-rigid foam according to the present invention will be described in more detail.

The silicone resin of the composition according to the invention is embodied by the following.

Silicone resin has a polymer of M and Q units having a structure of the formula (1) having a number average molecular weight of 1,000 to 10,000 and a ratio of M units to Q units of 0.1: 1 to 1.3: 1 (hereinafter referred to as MQ resin) It is a component dispersed in silicone oil and mainly related to adhesion, flexibility, elasticity, and the like.

[Formula 1]

Where

R is a hydroxy group, hydrogen, an aromatic ring having 6 to 12 ring members, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, or COOR ₃ (Wherein R ₃ is C ₁ -C ₁₂ alkyl or an aromatic ring having 6 to 12 ring members), preferably -Ph, -CH ₃ , -OPh, -OCH ₃ , -COOPh, or -COOCH ₃ .

Silicone resins are located between silicone oils and serve to bond them together. In particular, when the foam is foamed, the silicone oil is released between the fine cracks of the mold by the low surface tension at high temperature and high pressure to prevent the release time from being lowered.

Organosiloxane MQ resins polysiloxane can spleen called inherently R ₃ SiO _1/2 (M units) and SiO _4/2 of a polymer consisting of (Q unit), these resins are R ₂ SiO ₂ called the D and T units, respectively _{/ 2,} and R ₁ may comprise SiO _3/2 units for a portion. The term MQ resin, as used herein, means that on average it includes up to 10 mol% D and T units of the resin molecule.

The major factors that determine the properties of silicone resins are the resin's number average molecular weight (Mn) and the ratio of M and Q units.

The number average molecular weight (Mn) of the silicone resin used in the present invention is 1,000 to 10,000, preferably 3,000 to 7,000, more preferably 4,000 to 5,000. Here, if the number average molecular weight is less than 1,000, the silicone oil is prevented from being released into the mold groove, and thus the release force is not prevented. If the number average molecular weight is more than 10,000, dispersion is difficult during manufacture and the hardness of the release coating film becomes high. Cracks occur and are undesirable.

In addition, the ratio of M unit and Q unit is 0.1: 1 to 1.3: 1, preferably 0.3: 1 to 1.1: 1, more preferably 0.5: 1 to 0.9: 1, and the ratio of M unit and Q unit is 0.1 If lower than: 1, cracks are formed on the surface of the molded foam, and if it is more than 1.3: 1, cohesive strength of the molded foam is lowered, thereby reducing durability and insulation.

In the present invention, the amount of the silicone resin used is 5 to 20% by weight, more preferably 8 to 17% by weight. Herein, when the silicone resin is used in less than 5% by weight, it is difficult to express the characteristics of the silicone resin described above. When the silicone resin is more than 20% by weight, it is difficult to demould because the adhesiveness (Adhesion and Tack) is stronger than the release property.

The silicone oils of the compositions according to the invention are embodied by the following.

In the present invention, the silicone oil uses a cyclopolysiloxane having a -Si-O-Si- repeating unit structure having a number average molecular weight of 100 to 10,000.

Silicone oils generally use alkyl modified polysiloxanes containing alkyl groups as primary binders of the release agent and non-reactive functional groups of higher cycloaliphatic and acyclic aliphatic (i.e. alicyclic or linear or branched aliphatic). The silicone oil used in the present invention is a cyclopolysiloxane having a -Si-O-Si- repeating unit structure. Preferably, the number of Si-O-Si- repeating units is 3 to 6 cyclopolysiloxanes, and more preferably, the silicone oil of the present invention is a compound of formula 2 below.

[Formula 2]

Where

R ₁ and R ₂ are each independently an aromatic ring having 6 to 12 ring members, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, or COOR ₄ , wherein R ₄ is C ₁ -C ₁₂ alkyl or 6 To an aromatic ring having 12 to 12 ring members, preferably -Ph, -CH ₃ , -OPh, -OCH ₃ , -COOPh, or -COOCH ₃ , which is a reciprocal group with a hydroxyl group that is a hydrophilic group on the mold surface and the foam surface. Non-hydrophilic functional groups were used to decrease the functionality and increase dysplasia.

The number average molecular weight (Mn) of the silicone oil used in the present invention is 100 to 10,000, preferably 1,000 to 8,000, more preferably 3,000 to 6,000. In this case, when the number average molecular weight is less than 100, the release force of the silicone oil is severely released into the mold groove, and the release force is decreased. When the number average molecular weight exceeds 10,000, the viscosity is high and spray application is impossible, which is not preferable. In addition, if the viscosity is 20 to 500 cPs viscous polymer, if the viscosity is less than 20 cPs, the release of silicone oil into the mold groove is severe, the release force is reduced, if the viscosity exceeds 500 cPs silicone oil component It is not preferable because the surface of semi-rigid foam should be contaminated and washed with petroleum solvent.

The usage-amount of silicone oil is 73 to 90 weight%, More preferably, it is 77 to 86 weight%. If less than 73% by weight, the releasability is lowered, if it exceeds 90% by weight silicone oil on the molding foam after forming the semi-hard foam is not good because it must be washed with petroleum solvent.

The organosilanes of the compositions according to the invention are specified by the following. In general, organic silane is mainly used for the purpose of increasing adhesion between the silicone release agent and the molding mold, and there are various kinds of alkoxy modified, halogen modified, acrylic modified, epoxy modified silanes, etc. according to functional organic functional groups. In the present invention, an alkoxy group (-OR ₅ ) other than an amino group (-NH ₂ ), a mercapto group (-SH), and a halogen group (-F, -Cl, -Br, -I) in the functional organic functional group , Wherein R ₅ represents H, C ₁ -C ₁₂ alkyl, C ₂ -C ₁₂ alkenyl, or an aromatic ring having 6 to 12 ring members. Preferably -OPh, -OCH ₃ , -OCH ₂ CH ₃ , or -OCH = CH ₂ Use

If a silane containing an amino group and a mercapto group is used, it reacts with an addition catalyst to reduce the activity of the catalyst, and yellowing occurs when heated. When using a silane containing halogen group, reactivity is too fast and a strong acid, halogen acid, is generated as a by-product. Not good

In the present invention, the amount of organosilane used is 2 to 10% by weight, more preferably 4 to 8% by weight. When the organosilane is used at less than 2% by weight, the dispersibility between the silicone resin and the silicone oil is decreased, and when the organosilane is used at more than 10% by weight, the release property of the semi-rigid foam is not good.

The composition according to the invention may preferably further comprise the following surfactants.

In the case of aqueous emulsions, cationic surfactants or anionic surfactants are commonly used in the case of aqueous emulsions. Generally, polydimethylsiloxane, organosiloxane having siloxane units containing various organic groups, or mixtures thereof are used. In the present invention, a nonionic surfactant is used, and preferably polyoxymethylate, polyoxyethylate, or polyoxypropylate, which is an alcohol alkoxylate series, is used. At this time, it is preferable to use 0.1-1 weight% of surfactant. If it is less than 0.1% by weight, it is reacted with a resin premix (polyol, crosslinking agent, catalyst, blowing agent, pigment, and other additives) mixed with a urethane molding liquid and isocyanate (resin premix) as a counter part. The unreacted -OH and the hydrophilic group -OH, which is a hydrophilic group on the surface of the semi-rigid foam mold, lower the releasability, and when it exceeds 1% by weight, the silicone resin and the silicone oil Dispersion becomes difficult.

Hereinafter, the present invention will be described in detail with examples. However, the present invention is not limited by the examples.

<Examples and Comparative Examples>

All silicone compositions of Example and Comparative Examples (components and contents are shown in Table 1) were prepared in the same manner as one-part type.

First, silicone oils D ₃ , D ₄ , D ₅ , D ₆ Or a mixture of D ₃ to D ₆ (-Si-O-Si-repeated number of silicon oils with 3, 4, 5, and 6 is called D _{3 ,} D _{4 ,} D ₅ , and D ₆ , respectively, and generally If a single structure of D ₃ , D ₄ , D ₅ , and D ₆ is used in blending and it is difficult to separate each of the components of D ₃ , D ₄ , D ₅ , and D ₆ , a mixture thereof, D ₃ to D ₆ Premixed by blending each), followed by polyoxyethylate as a surfactant, followed by sufficient wetting with a dispermat, dissolver, or planetary mixer. After wetting, MQresin, a silicone resin, and methyltrimethoxysilane (MTMS), an organic silane, were added and dispersed to prepare a composition of the present invention. The composition is subjected to a vacuum defoaming step, and then D ₃ , D ₄ , D ₅ , and a silicone volatile oil of a mixture of D ₆ or D ₃ to D ₆ , an aliphatic hydrocarbon solvent such as n-hexane or n-heptane, or toluene, A solvent type release agent was prepared by diluting to less than 5% of solids in petroleum aromatic solvents such as xylene and benzene.

The prepared solvent-type release agent was applied to a molding mold so as to form a thin film by spraying, and the resin premix and isocyanate constituting the urethane molding foam were mixed and poured into a molding mold. Herein, the polyol has a number average molecular weight (Mn) of 4,000 to 7,000, and is of high activity type, and 2 to 3 functional groups (having 2 to 3 alcohol groups -OH) are used, and the crosslinking agent is ethylene glycol (EG), 1.4 Butanediol (BD), triethanolamine (TEOA), or glycerin were used, and the blowing agent used water and freon. In addition, isocyanate used a polymeric modified type having a functional group of about 2 to 2.7. Thereafter, the urethane molded foam was foamed at a high temperature of 200 ° C.

The release force of the release agent comprising the composition of the present invention is expressed as the number of demolds of the polyurethane foam (the number of molds that can be demolded after the silicone composition is applied once), and the demoulding does not split the edge portion, and pinholes and voids are formed on the skin of the urethane foam. Based on complete demoulding without, or coarse cells. Also, in order to check whether the gloss decreases over time by the silicone composition on the urethane foam skin after demolding, the desk type glossmeter (VG- 200, TRUCO Co., Ltd.) and tested according to ASTM D523 and JIS Z8741 at angles of ± 85 °, ± 60 °, ± 45 ° and ± 20 °, respectively.

<Release Force Test>

Examining the skin of the demolding specimens of the urethane molded foam prepared above for each composition, there are no pinholes, voids, coarse cells, etc., and the number of fully demolded specimens without cutting off the edge of the molded foam is shown in [Table 2]. Indicated.

Note 1) Release force: (S)-{(A) + (B) + (C)}

<Gloss Test of Urethane Molding Foam>

To determine whether the gloss decreases over time by the silicone composition on the skin of the urethane foam after demolding, use a gloss meter (VG-200, TRUCO) ± 85 °, ± 75 °, ± The test is conducted in accordance with the standards of ASTM D523, JIS Z8741 at an angle of 60 °, ± 45 °, ± 20 °, and the like, and is shown in Table 3 below, at intervals of 1, 3, 5, and 7 days based on the ± 60 ° angle. The change in glossiness over time is measured and shown in Table 4.

Note 2) ± 60 ° reference measurement data.

The composition of the present invention is not completely demolded by the hydroxyl group of moisture remaining during demolding in the case of the conventional aqueous emulsion release agent, and the appearance of the pinhole or void is generated on the surface of the foamed foam. It solved the disadvantages that were not good, and solved the problem that the appearance of yellowing when the mold was released due to the scale in the mold in the case of the general wax type release agent, and the gloss of the foam when using the conventional solvent release agent The decrease over time was improved.

In addition, since it has superior release properties compared to the conventional release agent for foam, it is useful for producing a mold semi-rigid foam.

Claims (3)

(A) 5 to 20% by weight of a silicone resin having a structure of Formula 1 having a number average molecular weight of 1,000 to 10,000 and a ratio of M units and Q units of 0.1: 1 to 1.3: 1; (B) 73 to 90% by weight of cyclopolysiloxane of the -Si-O-Si- repeating unit structure having a number average molecular weight of 100 to 10,000; And (C) an organosilane 2 containing an alkoxy group (-OR ₅ , wherein R ₅ represents H, C ₁ -C ₁₂ alkyl, C ₂ -C ₁₂ alkenyl, or an aromatic ring having 6 to 12 ring members) To about 10% by weight of the silicone composition. [Formula 1]

Where R is a hydroxy group, hydrogen, an aromatic ring having 6 to 12 ring members, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, or COOR ₃ , wherein R ₃ is C ₁ -C ₁₂ alkyl or 6 to Aromatic ring having 12 ring members. The composition of claim 1, wherein the cyclopolysiloxane of the -Si-O-Si- repeating unit structure is a compound of Formula 2. [Formula 2]

Where R ₁ and R ₂ are each independently an aromatic ring having 6 to 12 ring members, C ₁ -C ₁₂ alkyl, C ₁ -C ₁₂ alkoxy, or COOR ₄ Where R ₄ is C ₁ -C ₁₂ Alkyl or an aromatic ring having 6 to 12 ring members. The composition of claim 1, further comprising 0.1 to 1% by weight of nonionic surfactant.